Implement the functionality of create-pkg-config.sh in a Python module CmdCreatePkgConfig.py. This allows to remove create-pkg-config.sh and jw-build-functions.sh.
Note that the translation was done pretty literally to play it safe. More code can and should be removed by taking advantage of the fact that jw-projects.py knows more about the project than the shell scripts.
Signed-off-by: Jan Lindemann <jan@janware.com>