Add new `reviewers` field to application object in support of upcoming feedback revisions.

[ah-cog]

This field is being added to support the addition of an application reviewer assignment feature, which allows an application manager to assign specific Cogniac users as a reviewer of an application, which is a user that can provide "feedback" (e.g., bounding boxes and labels in the case of the box detection application type).

Assigned application reviewers must be assigned one of the two currently-supported application reviewer roles: (1) "reviewer", or (2) "annotator".

Users can be assigned as application reviewers by adding them into the reviewers field (list) in the application object at application creation time or by updating the application. For example, to update an application to assign a reviewer with the "reviewer" role:

POST /1/applications/{application_id}

{
    "reviewers": [
        {
            "user_email": "tenant.user@domain.com",
            "role": "reviewer"
        }
    ]
}

Note, "reviewer" could be replaced with "annotator" in the above example to assign the application reviewer with the annotator role.

Notes:

• The reviewer role concept here pertains only to assignment of roles of assigned application reviewers and is distinct from the tenant role assigned to users added to a tenant.
• As illustrated in the above example, each assigned application reviewer can be assigned exactly one application reviewer role.
• Each application can be assigned some reviewers with the "reviewer" role and some reviewers with the "annotator" role (e.g., 3 with "reviewer" and 6 with "annotator").
• Any application manager can add or update application reviewers and roles.
• When assigning or updating application reviewers, the entire reviewers list must be specified in the POST request to create or update an application (the default behavior of lists in the Cogniac Public API).