modules/python: refactored python auto detection code for Windows
modules/python: refactored python auto detection code for Windows

- No matter if python is found, we need to ensure we construct the correct
 call to "python" or "python_d" (for debug) under Windows.

pexip/meson,pexip/meson,pexip/meson,pexip/meson,pexip/meson,pexip/meson,pexip/meson,pexip/meson,pexip/meson,pexip/meson