Merge changes from topic "fdr_merge" into rvc-dev

* changes:
  libsnapshot: Allow forward merge on FDR
  libsnapshot: Place forward merge indicator for wipe
  libsnapshot: Add allow-forward-merge indicator.
  libsnapshot: Fix DataWipeAfterRollback test
  libsnapshot: Fix intermittent test failure due to missing null check.
  libsnapshot: dump rollback indicator