Assorted `run-make-support` maintenance
This PR should contain no functional changes.
- Commit 1: Removes the support library's CHANGELOG. In the very beginning, I thought maybe we would try to version this library. But this is a purely internal test support library, and it's just extra busywork trying to maintain changelog/versions. It's also hopelessly outdated.
- Commit 2: Resets version number to `0.0.0`. Ditto on busywork.
- Commit 3: Bump `run-make-support` to Edition 2024. The support library was already "compliant" with Edition 2024.
- Commit 4: Slightly organizes the support library dependencies.
- Commit 5: Previously, I tried hopelessly to maintain some manual formatting, but that was annoying because it required skipping rustfmt (so export ordering etc. could not be extra formatted). Give up, and do some rearrangements / module prefix tricks to get the `lib.rs` looking at least *reasonable*. IMO this is not a strict improvement, but I rather regain the ability to auto-format it with rustfmt.
- Commit {6,7}: Noticed in rust-lang/rust#143669 that we apparently had *both* {`is_msvc`, `is_windows_msvc`}. This PR removes `is_msvc` in favor of `is_windows_msvc` to make it unambiguous (and only retain one way of gating) as there are some UEFI targets which are MSVC but not Windows.
Best reviewed commit-by-commit.
r? `@Kobzol`
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