Agents don't have a direct relationship to a Client

[drewpayment]

Agents currently are assigned only to a User, which has a relationship to a Client. However, this doesn't work because users can have relationships to multiple Clients while we want agents to only be related to one Client at a time.

We need to add a Client relationship to the Agent entity, so that a user could have multiple agent records that were agnostic of each particular Client.

Clients are the highest level of separation in the web app and should be treated as such.

• Add client_id column to Agent entity
• Add query scope to Laravel entity that uses Auth::user() to automatically scope by client when the dev calls ->byClient()
• Update all "agent" API endpoints to incorporate client_id
• Update frontend models to have clientId

[drewpayment]

• Added client_id to Agent Laravel entity
• Updated AgentController->getAgents($activeOnly) to use ->byClient() query filter

[drewpayment]

Agents now have direct relationships to clients. Cleaned up some of the authorization logic that uses the logged in user's role.

There is a residual bug where if the user tries to save an existing form without changed data, the agent card UI breaks after it tries sending the API call. Need to disallow user from saving the dialog form if they haven't changed any fields on it.