4.0 renames

[technige]

This PR adds a handful of naming changes, largely around synchronising naming and the associated mental model throughout the product suite.

1. StatementResult has been renamed to Result along with all derivations and associated text.
2. Statement has been renamed to Query along with all derivations and associated text.
3. ExplicitTransaction has been renamed to UnmanagedTransaction along with all derivations and associated text.
4. Transaction functions and auto-commit transactions have been described as "managed" in several places, as a contrast to "unmanaged" in the context of (3).