Separate launcher icon and splash screen for AOSP and Google Contacts

Change in this package is the same as ag/2579098

Bug: 63887147
Bug: 63931514

Test: Both make build and gradle build packages/apps/Contacts.
Verified icon and splash screen on Nexus5x N, Pixel O, Nexus9 L
https://screenshot.googleplex.com/mGMJs48OC4J

Change-Id: I41f923f3784b6191d722c4fdf54cdc992e8ead40