Recognize dynamic res ids as valid

Shared libraries are assigned package id 0. Resource ids that start
with 0x00 are not invalid. This change changes is_valid to accept
dynamic resource ids and adds an is_valid_static method for when
an id must have a non-zero package id.

This also fixes an issue that made layouts in shared libraries that
use internal attributes exclude compiled resource ids from the binay
xml output.

Bug: 146491000
Test: Build a shared library with a layout that uses app attributes
      as well as android attribute and verify that all attributes
      have assigned resource ids using `aapt2 dump xmltree`

Change-Id: Ibc0407c610ffc98d7aaf233c37c065912ab0d516