!!! [v6r10] [CHANGE] Set file status for transformation as bulk op, plus logic in the client

For https://github.com/DIRACGrid/DIRAC/issues/1599

Few notes (might go in the "What's new? How to update" for this release, even if should not really affect anyone):
- the signature of TransformationDB().setFileStatusForTransformation changed a bit
- TransformationDB().setFileStatusForTransformation() and TransformationClient().setFileStatusForTransformation() are not returning any more a S_OK({'Failed':[], 'Successful':[]) dictionary. Instead, each operation is bulk, so it is either successful (S_OK()) or failed (S_ERROR())
- The ErrorCount for the files will always increase. The check for MaxReset files is done using the module operator
- The number of retries before setting a file in MaxReset can be set on the CS
- VOs can easily plug their own transformation files state machine