Use Rustc prefix for rustc attrs in AttributeKind

[clubby789]

cc #131229

Most rustc_... attrs have their variants named RustcAttrName, but several do not. Rename these attributes for consistency.

r? @jdonszelmann

[rustbot]

⚠️ #[rustc_allow_const_fn_unstable] needs careful audit to avoid accidentally exposing unstable
implementation details on stable.

cc @rust-lang/wg-const-eval

Some changes occurred to constck

cc @fee1-dead

Some changes occurred in compiler/rustc_passes/src/check_attr.rs

cc @jdonszelmann, @JonathanBrouwer

Some changes occurred to the CTFE machinery

cc @RalfJung, @oli-obk, @lcnr

Some changes occurred in compiler/rustc_attr_parsing

cc @jdonszelmann, @JonathanBrouwer

Some changes occurred in compiler/rustc_hir/src/attrs

cc @jdonszelmann, @JonathanBrouwer

[jdonszelmann]

At some point I even considered having a separate rustc attr enum so it would be Attr kind::RustC(RustcAttrKind::...). We can always still do that of course, not sure if we want that. But I do think this is nice for consistency. Dya agree @JonathanBrouwer?

[jdonszelmann]

r=me if you ack Jonathan, just want you to also be aware of changes here

[JonathanBrouwer]

This change makes a lot of sense to me. Thanks for making me aware :)
I'm not entirely sure of the value of a seperate enum for Rustc, mostly just think it will make the pattern matching in find_attr! slightly uglier, but don't have strong opinions about that.

@bors r=jdonszelmann,JonathanBrouwer rollup

[rust-bors]

📌 Commit 02bd3e8 has been approved by jdonszelmann,JonathanBrouwer

It is now in the queue for this repository.