AAPT would accept files with multiple periods in the filename as input.
This lead to cases explained in b/74999475. This change adds error
messages for files with multiple periods unless the legacy flag is
present. With the legacy flag present, AAPT2 will behave like AAPT
rather than throwing an error.
Test: Added tests to aapt2_tests
Bug: 73071563
Bug: 74999475
Change-Id: I28dfceeea7b39f8e4b9e6671e0fc8793cf388f52
