Improve JMESPath validation

[kjlippold]

Steps to Reproduce

Create a new data connection with an invalid JMESPath expression.
Run a task using the invalid JMESPath.

Expected Behavior

If possible, the API should reject invalid JMESPath expressions. Otherwise, when a task is run with an invalid JMESPath that couldn't be validated until runtime, the task should return an error message telling the user that the JMESPath was invalid or couldn't be used.

Actual Behavior

The API allows invalid JMESPath expressions through, and tasks return a generic error message when the expressions cause the task to fail.

Any additional comments?

No response