* [HUDI-839] Introducing rollback strategy using marker files
- Adds a new mechanism for rollbacks where it's based on the marker files generated during the write
- Consequently, marker file/dir deletion now happens post commit, instead of during finalize
- Marker files are also generated for AppendHandle, making it consistent throughout the write path
- Until upgrade-downgrade mechanism can upgrade non-marker based inflight writes to marker based, this should only be turned on for new datasets.
- Added marker dir deletion after successful commit/rollback, individual files are not deleted during finalize
- Fail safe for deleting marker directories, now during timeline archival process
- Added check to ensure completed instants are not rolled back using marker based strategy. This will be incorrect
- Reworked tests to rollback inflight instants, instead of completed instants whenever necessary
- Added an unit test for MarkerBasedRollbackStrategy
Co-authored-by: Vinoth Chandar <vinoth@apache.org>