MongoDB client Integration

Integrate MongoDB client in copilot. Test entity and request schema use for pilot requests.

This ticket will require the creation of some test data to be inserted into MongoDB. We'll need an `entitiy.json` which copilot will query based on `pilot_uuid` and examine for kek request authorization. Copilot will also add a database entry for each kek request based on the request schema.

Keys can still remain hard-coded, but should have IDs matching those in the `authorized_kek_ids` or `revoked_kek_ids` for testing.