Update process mount points when appop gets updated.

When an app is started, it's mountmode is dependent on
OP_REQUEST_INSTALL_PACKAGES. If user changes the appop grant of an app,
we need to update the mounts of any processes running in that app.

Bug: 121099965
Test: atest android.appsecurity.cts.ExternalStorageHostTest#testExternalStorageObbGifts
Change-Id: I606c4d9b338800637acb45b263c4673f210b1de8