Change keyword for setting output formats in Derivation_tf

Currently the keyword for setting the output DAOD formats in the new CA-based derivation framework transform Derivation_tf.py is requiredDerivedFormats. We have agreed that this is too long and since the keyword formats is available, we've decided to switch to this. Consequently once this MR is merged the new transform would be used as follows:

Derivation_tf.py --CA --inputAODFile aod.pool.root --outputDAODFile daod.pool.root --formats PHYS PHYSLITE ETC

Since this new transform isn't used in production yet, this MR will have no impact on any existing production or activities.