AAPT2: Fixed id parsing error

A previous change, editied the logic for parsing ids to allow for ids to
reference other ids. This change though caused a regression that made
ids in the form '<id name="name" />' cease to parse. This changes fixes
that regression.

Bug: 78513618
Test: Updated tests in ResourceParser_test.cpp
Change-Id: I3608bb764464e951a50910be55e199c6ec575d09