[clang] [Clang] Implement resolution for CWG1835 (PR #92957)

[Vlad Serebrennikov via cfe-commits]

Endilll wrote:

> Per [[basic.lookup.qual.general] p1](http://eel.is/c++draft/basic.lookup.qual.general#1), lookup for a member-qualified name is type-only if it's an identifier followed by ::;

Per my reading, type-only lookup is performed only for elaborated type specifiers (http://eel.is/c++draft/basic.lookup#elab-1.sentence-1) and base-specifiers (http://eel.is/c++draft/class.derived#general-2.sentence-4). What [basic.lookup.qual.general] p1 describes is much like type-only lookup, but namespaces are considered. Another important difference is that http://eel.is/c++draft/basic.lookup#general-4.sentence-2 do apply to lookup of identifiers followed by `::`.

Not saying that this materially changes anything, but we should be more cautions with terminology.

https://github.com/llvm/llvm-project/pull/92957