Use staging-public-group in framework SDK

To make S finalization easier, this changes the framework SDK so that
apps linking against it will be able to continue working as expected
after the first phase of SDK finalization.

During the first phase of SDK finalization, the resource ids of
resources that have not been removed are finalized.
staging-public-group tags are converted to staging-public-group-final
tags in order to encode into the framework what the staged resource id
of a finalized resource was. When an app recompiles, it will use the
finalized resource id. Then after all apps recompile, phase 2 of
finalization begins, in which the staging-public-group-final tags are
removed so apps can no longer use the staged resource ids.

Apps that link against the SDK (provided they are using a recent
version of aapt) will encode references to staged resources as
TYPE_DYNAMIC_REFERENCE and TYPE_DYNAMIC_ATTRIBUTE. The values of R
fields for staged resources are defined out-of-line to prevent them
from being inlined into apps linking agsint the SDK. This allows the
resource ids to change during phase 1 of API finalization.

Bug: 183413192
Test: `aapt2 diff` and resource ids stayed the same
Test: `aapt2 dump` of framework-res.apk and observe staged resources
Change-Id: Ie2275c608297a5f63dde8b1cf795415112cbcc24