Fix errors in template specialization with qualified arguments

[yut23]

This addresses the problem mentioned in the TODO comment in sphinxrenderer.py, which I ran into with this piece of code: https://github.com/AMReX-Astro/Microphysics/blob/b7fa023216305edce0ea4a8cff60e6a781a69400/util/microphysics_autodiff.H#L229-L234

The change in sphinxrenderer.py fixes the class name being cut off inside the template argument, corresponding to this warning:

breathe/documentation/source/specific.rst:247: WARNING: Invalid C++ declaration: Expected end of definition. [error at 15]
  template<> Foo >
  ---------------^

The change in filter.py fixes the class being duplicated outside its namespace, corresponding to these errors and warnings:

breathe/documentation/source/specific.rst:3: CRITICAL: Duplicate ID: "cpp_ns_template_specializationstructns2_1_1_trait_3_01ns1_1_1_foo_01_4_1ae96d840cc2c8f12b13e15f5b66dbdf03".
breathe/documentation/source/specific.rst:3: WARNING: Duplicate explicit target name: "cpp_ns_template_specializationstructns2_1_1_trait_3_01ns1_1_1_foo_01_4_1ae96d840cc2c8f12b13e15f5b66dbdf03".
breathe/documentation/source/specific.rst:3: CRITICAL: Duplicate ID: "cpp_ns_template_specializationstructns2_1_1_trait_3_01ns1_1_1_foo_01_4".
breathe/documentation/source/specific.rst:3: WARNING: Duplicate explicit target name: "cpp_ns_template_specializationstructns2_1_1_trait_3_01ns1_1_1_foo_01_4".

Before and after screenshots

Before	After

[AA-Turner]

cc @Rouslan

[Rouslan]

Hi @AA-Turner, why have you mentioned me? Did you want my input on something?

Since you brought this to my attention, I tested my own fork. The first problem identified in this pull request is already solved because I replaced the naive string split with a small hand-written parser. The second is not, and I will try to fix it later.