Add UWP (msvc) target support page

[bdbai]

• Added Platform Support page for x86_64-uwp-windows-msvc, i686-uwp-windows-msvc, thumbv7a-uwp-windows-msvc and aarch64-uwp-windows-msvc
  • Adding myself as a maintainer
  • Removing the ticks for thumbv7a-pc-windows-msvc and thumbv7a-uwp-windows-msvc as they do not currently build due to raw-dylib usage in std broke thumbv7a-*-windows-msvc targets #134565 and Attempt to fix ARM32 Windows backtrace-rs#685
• Fixed a few minor issues to let most of the UWP targets compile
• Happy new year to all!

r? jieyouxu

[rustbot]

Some changes occurred in src/doc/rustc/src/platform-support

cc @Noratrieb

[jieyouxu]

You probably need to run ./x fmt locally (or just use the fmt diff from the error message).

[jieyouxu]

Thanks for the PR, and happy new year to you as well. Could you split the library changes from the platform support doc changes, into two separate commits? It seems like here the first commit has some changes which were reverted by the second and third commit. But otherwise, this LGTM from the compiler side.

Thanks for signing up as the target maintainer for these targets!

[jieyouxu]

Suggestion:

Suggested change

	- @bdbai
	- [@bdbai](https://github.com/bdbai)

[bdbai]

Fixed in 2389daa

[jieyouxu]

cc @ChrisDenton (since you're both a libs reviewer and a Windows expert, in case you have any concerns)

[jieyouxu]

@rustbot author (on the commit history cleanup)

[ChrisDenton]

I'm ok with the libs changes once CI is happy with the formatting. Ideally this would be two separate PRs, one for the libs changes and one for the support update. But the libs change is small so it's not a big deal.