New Agency Proposal Screen

[maxachis]

A new data source may not have an associated agency in the database.

In these cases, we should be able to submit a new agency which can then be linked to the data source.

The way this process would work is:

1. We ensure the /agencies POST endpoint can submit a new agency
2. When such an agency is submitted, an ID is returned which can be associated with proposed data sources
3. We add onto the Source Collector Retool application such that, if an agency is not found, a new one can be proposed and immediately submitted.

This is all predicated on the assumption of admin-only access. If we ever open these components up to non-admins, some changes may need added, including:

1. Modification to the agencies table to replace the approved column with multiple statuses such as pending, approved, rejected
2. Being able to submit pending agencies and receive an ID that can be used for data sources (this would require modifying the /agencies endpoint or the creation of a new non-admin endpoint)
3. Modifying the /match/agencies endpoint to optionally allow pending agencies
4. Being allowed to submit a pending agency to a pending data source
5. Determining how to handle those data sources if the pending agency is rejected.