rebased version

[Chobsz]

rebased version of previous PR #41

To enable masking and unmasking of single models or sources, functionality has been added as an optional parameter [resource_name].
The changeset should be backwards compatible.

I found the commands for unmasking too broad, affecting more resources than needed when applying of unapplying them.
I introduced this optional parameter, to quickly mask or unmask just 1 resource (sourcename from yamlfile) or nodename/foldername for model.
The old way, all sources would be unmasked during the post-hook or on-run-end, leaving unnecisary data exposed.

[Chobsz]

dbt run-operation apply_masking_policy --args '{"resource_type": "models","resource_name": "afas" }'

Works as designed, also tested in database.

dbt run-operation unapply_masking_policy --args '{"resource_type": "models","resource_name": "afas" }'

Works as designed, also tested in database.

dbt run-operation apply_masking_policy --args '{"resource_type": "sources","resource_name": "qisdm_replica_dbo" }'

Works as designed, also tested in database.

dbt run-operation unapply_masking_policy --args '{"resource_type": "sources","resource_name": "qisdm_replica_dbo" }'

Works as designed, also tested in database.