Reapply "[Clang][Sema] Fix crash when 'this' is used in a dependent class scope function template specialization that instantiates to a static member function (#87541, #88311)" (#88731)

Reapplies #87541 and #88311 (again) addressing the bug which caused
expressions naming overload sets to be incorrectly rebuilt, as well as
the bug which caused base class members to always be treated as overload
sets.

The primary change since #88311 is `UnresolvedLookupExpr::Create` is called directly in `BuildPossibleImplicitMemberExpr` with `KnownDependent` as `true` (which causes the expression type to be set to `ASTContext::DependentTy`). This ensures that any further semantic analysis involving the type of the potentially implicit class member access expression is deferred until instantiation.

GitOrigin-RevId: 5c4b923c727767c9e6ad16324c559a1a92616171
20 files changed