Catch YAML specification errors

[beckydvn]

• Raise exception if user tries to create a clarify action (through slot_fill or otherwise) for a context variable with a flag type known
• Raise exception if the user uses names that would be invalid in PDDL (spaces, etc.)
• Any actions with generated names (e.g. action names or intents from slot_fill) need to be checked against existing names in the YAML. Raise an exception if a duplicate occurs.
• For slot_fill actions, enforce you can’t have single-slot specifications if you only have one entity

[haz]

There already a dedicated place for confirming the yaml? These seem like a great start for what should be a common practice of scanning the yaml on ingestion.

[beckydvn]

Right now it's just the parsing file that converts it to the hovor JSON. It would be ideal to have a "scan" before parsing anything, but for the "custom" actions that wouldn't work. So those exceptions would have to be handled within the parsing module