Rollup merge of #139770 - nnethercote:rename-LifetimeName, r=BoxyUwU

Rename `LifetimeName` as `LifetimeKind`.

It's a much better name, more consistent with how we name such things.

Also rename `Lifetime::res` as `Lifetime::kind` to match. I suspect this field used to have the type `LifetimeRes` and then the type was changed but the field name remained the same.

r? ``@BoxyUwU``

Author: matthiaskrgr

Diff for: src/ty.md

@@ -61,11 +61,11 @@ Here is a summary:
 | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | Describe the *syntax* of a type: what the user wrote (with some desugaring).  | Describe the *semantics* of a type: the meaning of what the user wrote. |
 | Each `rustc_hir::Ty` has its own spans corresponding to the appropriate place in the program. | Doesn’t correspond to a single place in the user’s program. |
-| `rustc_hir::Ty` has generics and lifetimes; however, some of those lifetimes are special markers like [`LifetimeName::Implicit`][implicit]. | `ty::Ty` has the full type, including generics and lifetimes, even if the user left them out |
+| `rustc_hir::Ty` has generics and lifetimes; however, some of those lifetimes are special markers like [`LifetimeKind::Implicit`][implicit]. | `ty::Ty` has the full type, including generics and lifetimes, even if the user left them out |
 | `fn foo(x: u32) → u32 { }` - Two `rustc_hir::Ty` representing each usage of `u32`, each has its own `Span`s, and `rustc_hir::Ty` doesn’t tell us that both are the same type | `fn foo(x: u32) → u32 { }` - One `ty::Ty` for all instances of `u32` throughout the program, and `ty::Ty` tells us that both usages of `u32` mean the same type. |
-| `fn foo(x: &u32) -> &u32)` - Two `rustc_hir::Ty` again. Lifetimes for the references show up in the `rustc_hir::Ty`s using a special marker, [`LifetimeName::Implicit`][implicit]. | `fn foo(x: &u32) -> &u32)`- A single `ty::Ty`. The `ty::Ty` has the hidden lifetime param. |
+| `fn foo(x: &u32) -> &u32)` - Two `rustc_hir::Ty` again. Lifetimes for the references show up in the `rustc_hir::Ty`s using a special marker, [`LifetimeKind::Implicit`][implicit]. | `fn foo(x: &u32) -> &u32)`- A single `ty::Ty`. The `ty::Ty` has the hidden lifetime param. |
 
-[implicit]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_hir/hir/enum.LifetimeName.html#variant.Implicit
+[implicit]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_hir/hir/enum.LifetimeKind.html#variant.Implicit
 
 **Order**
 
@@ -323,4 +323,4 @@ When looking at the debug output of `Ty` or simply talking about different types
 - Generic parameters: `{name}/#{index}` e.g. `T/#0`, where `index` corresponds to its position in the list of generic parameters
 - Inference variables: `?{id}` e.g. `?x`/`?0`, where `id` identifies the inference variable
 - Variables from binders: `^{binder}_{index}` e.g. `^0_x`/`^0_2`, where `binder` and `index` identify which variable from which binder is being referred to
-- Placeholders: `!{id}` or `!{id}_{universe}` e.g. `!x`/`!0`/`!x_2`/`!0_2`, representing some unique type in the specified universe. The universe is often elided when it is `0`
+- Placeholders: `!{id}` or `!{id}_{universe}` e.g. `!x`/`!0`/`!x_2`/`!0_2`, representing some unique type in the specified universe. The universe is often elided when it is `0`