OMS7-N: installd: add command 'rmidmap'

Add an installd command to remove an idmap file. This is the inverse of
the 'idmap' command and is intended for clean-up once an idmap file is
no longer needed because an APK was removed, etc.

Change-Id: I98cb26a51d03d7babda6b7b46b6a328abb032836
3 files changed