AAPT2: Allow arbitrary entry names with aapt2 optimize

Presumably, the apps build fine for the developers, so just
feed the existing names through without validation. Validation
still exists when building an app from source.

Bug: 36051854
Change-Id: Idc64ee91b08dce67d3c28f3c5284a7afa1312df1
Test: run aapt2 optimize on the apks from b/36051854 and build aapt2_tests