`deref_patterns`: support string and byte string literals in explicit `deref!("...")` patterns

When `deref_patterns` is enabled, this allows string literal patterns to be used where `str` is expected and byte string literal patterns to be used where `[u8]` or `[u8; N]` is expected. This lets them be used in explicit `deref!("...")` patterns to match on `String`, `Box<str>`, `Vec<u8>`, `Box<[u8;N]>`, etc. (as well as to match on slices and arrays obtained through other means). Implementation-wise, this follows up on rust-lang#138992: similar to how byte string literals matching on `&[u8]` is implemented, this changes the type of the patterns as determined by HIR typeck, which informs const-to-pat on how to translate them to THIR (though strings needed a bit of extra work since we need references to call `<str as PartialEq>::eq` in the MIR lowering for string equality tests).

This PR does not add support for implicit deref pattern syntax (e.g. `"..."` matching on `String`, as `string_deref_patterns` allows). I have that implemented locally, but I'm saving it for a follow-up PR[^1].

This also does not add support for using named or associated constants of type `&str` where `str` is expected (nor likewise with named byte string constants). It'd be possible to add that if there's an appetite for it, but I figure it's simplest to start with literals.

This is gated by the `deref_patterns` feature since it's motivated by deref patterns. That said, its impact reaches outside of deref patterns; it may warrant a separate experiment and feature gate, particularly factoring in the follow-up[^1]. Even without deref patterns, I think there's probably motivation for these changes.

The update to the unstable book added by this will conflict with rust-lang#140022, so they shouldn't be merged at the same time.

Tracking issue for deref patterns: rust-lang#87121

r? `@oli-obk`
cc `@Nadrieril`

[^1]: The piece missing from this PR to support implicit deref pattern syntax is to allow string literal patterns to implicitly dereference their scrutinees before matching (see rust-lang#44849). As a consequence, it also makes examples like the one in that issue work (though it's still gated by `deref_patterns`). I can provide more information on how I've implemented it or open a draft if it'd help in reviewing this PR.

Rollup of 23 pull requests

Successful merges:

 - rust-lang#139261 (mitigate MSVC alignment issue on x86-32)
 - rust-lang#139307 (std: Add performance warnings to HashMap::get_disjoint_mut)
 - rust-lang#139700 (Autodiff flags)
 - rust-lang#139752 (set subsections_via_symbols for ld64 helper sections)
 - rust-lang#139809 (Don't warn about `v128` in wasm ABI transition)
 - rust-lang#139852 (StableMIR: Implement `CompilerInterface`)
 - rust-lang#139945 (Extend HIR to track the source and syntax of a lifetime)
 - rust-lang#140028 (`deref_patterns`: support string and byte string literals in explicit `deref!("...")` patterns)
 - rust-lang#140139 (rustc_target: Adjust RISC-V feature implication)
 - rust-lang#140143 (Move `sys::pal::os::Env` into `sys::env`)
 - rust-lang#140148 (CI: use aws codebuild for job dist-arm-linux)
 - rust-lang#140150 (fix MAX_EXP and MIN_EXP docs)
 - rust-lang#140172 (Make algebraic functions into `const fn` items.)
 - rust-lang#140177 ([compiletest] Parallelize test discovery)
 - rust-lang#140181 (Remove `synstructure::Structure::underscore_const` calls.)
 - rust-lang#140184 (Update doc of cygwin target)
 - rust-lang#140186 (Rename `compute_x` methods)
 - rust-lang#140187 ([AIX] Handle AIX dynamic library extensions within c-link-to-rust-dylib run-make test)
 - rust-lang#140191 (Remove git repository from git config)
 - rust-lang#140194 (minicore: Have `//@ add-core-stubs` also imply `-Cforce-unwind-tables=yes`)
 - rust-lang#140195 (triagebot: label minicore changes w/ `A-test-infra-minicore` and ping jieyouxu on changes)
 - rust-lang#140202 (Make #![feature(let_chains)] bootstrap conditional in compiler/)
 - rust-lang#140214 (Remove comment about handling non-global where bounds with corresponding projection)

r? `@ghost`
`@rustbot` modify labels: rollup

…iaskrgr

Rollup of 9 pull requests

Successful merges:

 - rust-lang#134446 (Stabilize the `cell_update` feature)
 - rust-lang#139307 (std: Add performance warnings to HashMap::get_disjoint_mut)
 - rust-lang#139450 (Impl new API `std::os::unix::fs::mkfifo` under feature `unix_fifo`)
 - rust-lang#139809 (Don't warn about `v128` in wasm ABI transition)
 - rust-lang#139852 (StableMIR: Implement `CompilerInterface`)
 - rust-lang#139945 (Extend HIR to track the source and syntax of a lifetime)
 - rust-lang#140028 (`deref_patterns`: support string and byte string literals in explicit `deref!("...")` patterns)
 - rust-lang#140181 (Remove `synstructure::Structure::underscore_const` calls.)
 - rust-lang#140232 (Remove unnecessary clones)

r? `@ghost`
`@rustbot` modify labels: rollup

Rollup merge of rust-lang#140028 - dianne:lit-deref-pats-p1, r=oli-obk

`deref_patterns`: support string and byte string literals in explicit `deref!("...")` patterns

When `deref_patterns` is enabled, this allows string literal patterns to be used where `str` is expected and byte string literal patterns to be used where `[u8]` or `[u8; N]` is expected. This lets them be used in explicit `deref!("...")` patterns to match on `String`, `Box<str>`, `Vec<u8>`, `Box<[u8;N]>`, etc. (as well as to match on slices and arrays obtained through other means). Implementation-wise, this follows up on rust-lang#138992: similar to how byte string literals matching on `&[u8]` is implemented, this changes the type of the patterns as determined by HIR typeck, which informs const-to-pat on how to translate them to THIR (though strings needed a bit of extra work since we need references to call `<str as PartialEq>::eq` in the MIR lowering for string equality tests).

This PR does not add support for implicit deref pattern syntax (e.g. `"..."` matching on `String`, as `string_deref_patterns` allows). I have that implemented locally, but I'm saving it for a follow-up PR[^1].

This also does not add support for using named or associated constants of type `&str` where `str` is expected (nor likewise with named byte string constants). It'd be possible to add that if there's an appetite for it, but I figure it's simplest to start with literals.

This is gated by the `deref_patterns` feature since it's motivated by deref patterns. That said, its impact reaches outside of deref patterns; it may warrant a separate experiment and feature gate, particularly factoring in the follow-up[^1]. Even without deref patterns, I think there's probably motivation for these changes.

The update to the unstable book added by this will conflict with rust-lang#140022, so they shouldn't be merged at the same time.

Tracking issue for deref patterns: rust-lang#87121

r? ``@oli-obk``
cc ``@Nadrieril``

[^1]: The piece missing from this PR to support implicit deref pattern syntax is to allow string literal patterns to implicitly dereference their scrutinees before matching (see rust-lang#44849). As a consequence, it also makes examples like the one in that issue work (though it's still gated by `deref_patterns`). I can provide more information on how I've implemented it or open a draft if it'd help in reviewing this PR.