Create manifest_utils library target.

This utility can also be used for parsing and
managing the Android Manifest for apex under
system/apex/apexer.

Test:
python manifest_fixer_test.py
python manifest_check_test.py

BUG: 148198056
Change-Id: Iffe465b5f36b2a3fbf81414d6f19e241c5f5648f