Add <staging-public-group-final> to aapt2

To allow apps that compiled against a pre-release SDK to continue
working for a period of time after API finalization, a new tag,
<staging-public-group-final>, has been added to aapt2.

When finalizing the framework resource API, converting
<staging-public-group> tags to <staging-public-group-final> will
cause aapt2 to generate the resource table so that there is a resource
entry for the old non-finalized (staged) resource ID and another entry
for the finalized resource ID of newly finalized resources. This allows
an application that compiled against the pre-release SDK to continue
resolving resources using pre-release resource IDs.

All references to pre-release resource IDs will be rewritten to their
finalized resource IDs through the information stored in the new staged
alias chunk. This allows applications compiled against
<staging-public-group> resources to use the newly finalized
resource ID without re-compilation.

When an application is re-compiled against the SDK with
<staging-public-group-final> tags, the application will use the
finalized resource IDs.

This change limits the use of the alias chunk to the framework for S.

Bug: 183411356
Test: aapt2_test
Change-Id: Iba1c3033c3c2f32de8e4a19b58d3921c971092c4