Simplify module-info.json by leaving out optional fields

Every field in module-info.json has at least "[]".  Add functions to
only write the values when they are non-empty to reduce the size
and ease comparison when module-info.json is written by Soong.

Bug: 309006256
Test: atest --host toybox-gtests --test-timeout=120000
Change-Id: I200e8c8fd9727b4cffa9b82318f4433fd630e933