feat+fix(engine)!: Support enums and defaults in Action Templates

[topher-lo]

What changed?

• Fixes issue where arguments with defaults do not show up in the action run. Fixed by validated arguments (i.e. creating the expectation model) before running the template action.
• Updates validate_args method to return model_schema_inputs with json mode (i.e. enum instances are coerced into string)
• Drop unused validate conditional in _run_action_direct (this path isn't used anywhere in the code)
• Replaced all references to tracecat_registry._internal.exceptions.TracecatValidationError with tracecat.types.exceptions.TracecatValidationError

Note: we had to make key in TracecatValidationError optional and serializable in order to bypass Ray's issue reraising instances of exceptions. ray-project/ray#8948. Unsure why but unless all init variables for the exception are optional, ray seems to keep raising the TypeError with missing key. See reference for example.

References

[daryllimyt]

minor change

[daryllimyt]

LGTM