Bring over the build.py script and its associated scripts from the
scripts subdirectory of the jami-project.git as of commit
14a328b88007bff5ea21650fb00f6d4ead14cf02, with small changes to
simplify and drop unneeded parts and adapt to their new locations.
Change-Id: I500702854e45392a931ff7505e191b966015cd16
This build.py script is Windows-specific, as such we move it to
extras/scripts/build-windows.py in preparation for importing the main
cross-platform build.py script from the jami-project.git repository.
Change-Id: I7d7d98ffb67f7fcdea767d28fd8cdefabea98d4b
