Currently, clang postpones all semantic analysis of unary operators with
operands of pointer/pointer to member/array/function type until
instantiation whenever that type is dependent (e.g. `T*` where `T` is a
type template parameter). Consequently, the uninstantiated AST nodes all
have the type `ASTContext::DependentTy` (which, for the purposes of
#90152, is undesirable as that type may be the current instantiation!
(e.g. `*this`))
This patch moves the point at which we perform semantic analysis for
such expression to be prior to instantiation.
