✨ Add a couple of useful name utilities

[elbeno]

Problem:

• Using names in metaprogramming often involves matching on a name, using a quoted metafunction.

Solution:

• Add same_name and matching_name.

[nikhilshahani]

Suggestion for a follow-up PR: The existing ct_string documentation covers the core string and cts_t APIs, but the named-type helpers are not documented yet. It would be useful to add a small section covering named, with_name, name_of_v, constant_name_of_t, and constant_name_of_v, along with the new matching_name / same_name predicates and their _q forms.