[clang] [clang] Split up `SemaDeclAttr.cpp` (PR #93966)

[Erich Keane via cfe-commits]

================
@@ -3825,6 +3843,115 @@ class Sema final : public SemaBase {
 
   void redelayDiagnostics(sema::DelayedDiagnosticPool &pool);
 
+  /// Diagnose mutually exclusive attributes when present on a given
----------------
erichkeane wrote:

Where did this section of stuff come from?  At least the first 2 are attribute related and might be better in the Attr.td with a SemaRef, perhaps a few others as well.

https://github.com/llvm/llvm-project/pull/93966