tests: Move to Android.bp.

Also separate libupdater_defaults out to be shareable.

It turns out the `data` property in `cc_test` doesn't follow symlinks as
LOCAL_TEST_DATA does in Android.mk. This CL creates a filegroup in
top-level Android.bp in order to pick up the testdata for ResourcesTest.

Test: `mmma -j bootable/recovery` with aosp_marlin-userdebug
Test: Run recovery_{unit,component,manual}_test on marlin.
Test: Run recovery_host_test.
Change-Id: I4532ab25aeb83c0b0baa8051d5fe34ba7b910a35