[clang] [Lifetime Safety] Distinguish attributed/inferred lifetimebound diagnostics (PR #220248)

[Utkarsh Saxena via cfe-commits]

================
@@ -2112,7 +2112,7 @@ void uaf_union() {
     U u = U{"hello"};
     U* up = &u;   // expected-warning {{local variable 'u' does not live long enough}}
     view = up->s; // expected-note {{local variable 'up' aliases the storage of local variable 'u'}} \
-                  // expected-note {{expression aliases the storage of local variable 'u' because the implicit object parameter is lifetimebound}}
+                  // expected-note {{expression aliases the storage of local variable 'u' because the implicit object parameter is inferred as lifetimebound}}
----------------
usx95 wrote:

I think mentioning `lifetimebound` could be quite confusing as there is no function call.  This is essentially field access and and not a lifetimebound call. 
Definitely belongs to a separate PR.

https://github.com/llvm/llvm-project/pull/220248