[aapt2] Always generate code for permissions

We will generate the String constant in Manifest.java for a permission
or permission group even if it is removed via feature flag. This is so
that code referencing the string will still compile.

Bug: 297373084
Bug: 318014882
Test: atest aapt2_tests
Test: Modified framework-res to build with SDK version 34 and forced
removal of a permission with a disabled feature flag. The entire
Android source could still be built even if the framework-res.apk no
longer had the removed permission in the manifest.

Change-Id: I982a8988e35e09e73bcbe065f0d7cf47c2907d54