Support parsing C++ templates (at least concrete specializations)

What is the feature you'd like to have?
The type parser should support parsing C++ template concrete specializations. Specifically concrete specializations and specifically just parsing into types, i.e. this does not involve creating templates in the typesystem like #3305.

Is your feature request related to a problem?
I want to import C++ headers which use templates, like things that use std::vector<int>

Are any alternative solutions acceptable?
I can manually create types for all of the template stuff, but that is tedious and error prone.

Additional Information:
Need to extend clang_svcs.cpp ClangTypeToBinja and add CType::TemplateSpecialization. Probably also need to add a bunch of other clang structures to deal with the scaffolding around the templates, but with any luck this can be limited to only fully concrete types for which a layout and fields can be generated.

Start in clang_svcs.cpp at ClangTypeToBinja and inspect CType::TemplateSpecialization, along with the related discussion in issue #3305. Determine the additional Clang structures needed for fully concrete specializations, then verify that headers using types such as std::vector import into concrete types with layout and fields.