A tracking issue for CLI comments related to F2PY.

• Recognize arbitrary extensions to be parsed as F77 or other (Related to ENH: Have f2py handle hybrid F77/F90 codebases #9928 and Make numpy.distutils recognize Fortran 2003 and Fortran 2008 files #5486)
• Use argparse and sub-parsers
• Finalize full test coverage for f2py2e (current CLI)
• Document the breaking changes due to np.distutils deprecation

CC @melissawm @pearu @NamamiShanker