Syntax highlighting for default functions

Python 3.10 was recently released and it has new soft keywords (match case) and they kind of implemented them (waiting for release developer.blender.org/rBc6ed879f9aa7cd863f146cc7104f16cfe8a73e8a ). And I remembered that blender has no highlighting for default functions.

Highlighting in PyCharm

I analyzed code a bit and realized that it's not so hard to implement, even though I'm not good at C, but I can a little bit with implementation of default functions structure and also I decided to split these structures into two types: txtfmt_py_default_functions, txtfmt_py_type_converters.

And it will be more correct to give for "txtfmt_py_default_functions" - purple color.

For "txtfmt_py_type_converters" - red. Here's half of all the work done (I think so), I hope this gets implemented: