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
diff --git a/tools/aapt2/Resources.proto b/tools/aapt2/Resources.proto
index b45c040..95b7949 100644
--- a/tools/aapt2/Resources.proto
+++ b/tools/aapt2/Resources.proto
@@ -190,6 +190,12 @@
   uint32 overlayable_idx = 4;
 }
 
+// The staged resource ID definition of a finalized resource.
+message StagedId {
+  Source source = 1;
+  uint32 staged_id = 2;
+}
+
 // An entry ID in the range [0x0000, 0xffff].
 message EntryId {
   uint32 id = 1;
@@ -222,6 +228,9 @@
   // The set of values defined for this entry, each corresponding to a different
   // configuration/variant.
   repeated ConfigValue config_value = 6;
+
+  // The staged resource ID of this finalized resource.
+  StagedId staged_id = 7;
 }
 
 // A Configuration/Value pair.