Add new shim apex signed by a key with rollback capability

If a key is rotated such that it still trusts the old key (i.e, has
rollback capability for the old key), then the old key can continue to
update the package. A new shim is required to test such scenarios.

Bug: 136002636
Test: builds successfully
Change-Id: Id6fd50122d70b9f2593145f434d3e6bc50256240
1 file changed