[AST] Preserve more structure in UsingEnumDecl node.
- store NestedNameSpecifier & Loc for the qualifiers
This information was entirely missing from the AST.
- expose the location information for qualifier/identifier/typedefs as typeloc
This allows many traversals/astmatchers etc to handle these generically along
with other references. The decl vs type split can help preserve typedef
sugar when https://github.com/llvm/llvm-project/issues/57659 is resolved.
- fix the SourceRange of UsingEnumDecl to include 'using'.
Fixes https://github.com/clangd/clangd/issues/1283
Differential Revision: https://reviews.llvm.org/D134303
15 files changed: