Unify the recovery UI for pixel 3+

The Pixel 3 and 4 are using the identical RecoveryUI class. So
consolidate them into the pixel common directory. This will ease the
work to unify the vendor space /misc access later.

Bug: 144810561
Test: wipe data in bramble and redfin
Change-Id: I43b7d04fe65ce919eb5c81a39034f50ce2ca9626
Signed-off-by: Chenglu Lin <chenglulin@google.com>