Add CtsShim apks to shim apex

Also relax the shim validation logic a bit to accept shim packages that
are missing certain files. This eases the roll-out of new packages.

Bug: 138429615
Test: Verified booting with existing CTS Shim prebuilts, and with new
CTS shim prebuilts containing APK-in-APEX.
Change-Id: Ie91a923594e3ef68fc768562258a74bf2e1e6b57
1 file changed