[clang] [Clang] Partially reapply "Refactor instantiation of declarations within concepts" (PR #223311)

[Corentin Jabot via cfe-commits]

================
@@ -589,6 +589,9 @@ features cannot lower the translation-unit ABI level;
 - Fixed a crash when module directive export module foo not following a
   semicolon and there are no rest pp-tokens in current module file. (#GH187771)
 
+- Fixed concept evaluation bugs where some declarations were not added to
+  the current instantiation scope. (#GH198052)
+
----------------
cor3ntin wrote:

```suggestion
- Fixed concept evaluation bugs where some declarations were not added to
  the current instantiation scope. (#GH198052) (#GH223220)

```

https://github.com/llvm/llvm-project/pull/223311