[clang-tidy] Add redundant qualified alias check (#180404)
Introduce `readability-redundant-qualified-alias` to flag identity type
aliases that repeat a qualified name and suggest using-declarations when
safe. The check is conservative: it skips macros, elaborated keywords,
dependent types, and templates. `OnlyNamespaceScope` controls whether
local/class scopes are included (default `false`).
Depends on: #183940 #183941
