Split gen_bp_files, make Android.bp idempotent.

Split gen_bp_files for future use of new build_props
function. Sort the data output to the Android.bp file so
that the script does not depend on the sort of the keys
in the various dictionaries.

Bug: 157967325
Test: verify that vendor snapshot content is identical
Test: verify Android.bp is sorted by arch, variation, name
Change-Id: I438f8611ad460bccfcae99441ad7c60aa3b68c49
1 file changed