AAPT2: Loosen loading apk format requirements

The Android runtime and AAPT are more lenient of apk format, allowing
for duplicate enty, types, and configs. This change loosens the
ResourceTable's checks on resource uniqueness when apks are loaded; not
when ResourceTables are being created by aapt2.

Bug: 36051266
Test: Tested using apks in bug with allow_duplicates on and off
Change-Id: I9296417bf2dc53e1e891479a53679a0388210d50