Enable execution of OGC data processing requests with arbitrary parameter values

[LucaCinquini]

Currently, we can only submit OGC execution requests which use the default parameter values. We must improve consistency between the OGC API and the Airflow DAG specification both when the process is deployed and executed. This involves augmenting the process definition in the database, and validate that the OGC requests are compatible with the (existing) DAG.

Specifically (from Slack conversation):

There are two rounds of validation that are not yet integrated.
o Validation that OGC process input fields correctly map to Airflow DAG input fields during OGC process deployment time.

• Example (during OGC process deployment): An error should be thrown if the Airflow DAGs inputs are not a subset of available OGC process inputs.
  o Validation that OGC execution values conform to the schema for the OGC process inputs (as defined during the deployment of the process).
• Example (during OGC process execution): An error should be thrown if a string value was passed for an OGC process input that only accepts integer values.