gh-113317: Argument Clinic: Add libclinic.clanguage (#117455)

Add libclinic.clanguage module and move the following classes and
functions there:

* CLanguage
* declare_parser()

Add libclinic.codegen and move the following classes there:

* BlockPrinter
* BufferSeries
* Destination

Move the following functions to libclinic.function:

* permute_left_option_groups()
* permute_optional_groups()
* permute_right_option_groups()