Auto merge of #124356 - fmease:fewer-magic-numbers-in-names, r=lcnr

Cleanup: Replace item names referencing GitHub issues or error codes with something more meaningful

**lcnr** in https://github.com/rust-lang/rust/pull/117164#pullrequestreview-1969935387:

> […] while I know that there's precendent to name things `Issue69420`, I really dislike this as it requires looking up the issue to figure out the purpose of such a variant. Actually referring to the underlying issue, e.g. `AliasMayNormToUncovered` or whatever and then linking to the issue in a doc comment feels a lot more desirable to me. We should ideally rename all the functions and enums which currently use issue numbers.

I've grepped through `compiler/` like crazy and think that I've found all instances of this pattern.
However, I haven't renamed `compute_2229_migrations_*`. Should I?

The first commit introduces an abhorrent and super long name for an item because naming is hard but also scary looking / unwelcoming names are good for things related to temporary-ish backcompat hacks. I'll let you discover it by yourself.

Contains a bit of drive-by cleanup and a diag migration bc that was the simplest option.

r? lcnr or compiler

compiler/rustc_hir_analysis/src/errors.rs

@@ -1666,3 +1666,13 @@ pub struct NonConstRange {
     #[primary_span]
     pub span: Span,
 }
+
+#[derive(Diagnostic)]
+#[diag(hir_analysis_invalid_receiver_ty, code = E0307)]
+#[note]
+#[help(hir_analysis_invalid_receiver_ty_help)]
+pub struct InvalidReceiverTy<'tcx> {
+    #[primary_span]
+    pub span: Span,
+    pub receiver_ty: Ty<'tcx>,
+}