Add DocDB mongo client that uses ssh tunnel

[helen-m-lin]

User story

As a user, I want to use a mongo client that uses a ssh tunnel, so I can access the AIND metadata document db more efficiently.

Acceptance criteria

• [x] Given a user uses the new mongo client provided in aind-data-access-api, they can connect to the AIND metadata docdb through a ssh tunnel with their database credentials.
• [ ] Other relevant utility methods can be added.

Sprint Ready Checklist

• [x] 1. Acceptance criteria defined
• [x] 2. Team understands acceptance criteria
• [x] 3. Team has defined solution / steps to satisfy acceptance criteria
• [x] 4. Acceptance criteria is verifiable / testable
• [x] 5. External / 3rd Party dependencies identified
• [x] 6. Ticket is prioritized and sized

Notes

Add any helpful notes here.

[helen-m-lin]

Relevant utility methods can be added at a later date. For now, we have a new doc db client that starts the ssh tunnel and docdb connection context. The metadata_index/data_assets collection can be accessed with doc_db_client.collection, like so:

with DocumentDbSSHClient(credentials=credentials) as doc_db_client:
    filter = {"subject.subject_id": "123456"}
    projection = {
        "name": 1, "created": 1, "location": 1, "subject.subject_id": 1, "subject.date_of_birth": 1,
    }
    response = list(doc_db_client.collection.find(filter=filter, projection=projection))

Readme has been updated with relevant setup.