Redundant JobType enum

[abyrd]

In the MonitorableJob class we have an enum listing the types of monitorable jobs. However monitorable jobs are all represented by subclasses of the MonitorableJob class. This enum is redundant. Each subclass should either override a function returning a unique string, or (perhaps better) the shared superclass should just define a public function returning the simple class name so it's visible when the instances are serialized to JSON.

[landonreed]

Any such change on the server would need to be accompanied by a corresponding UI fix to the check for this value in this switch statement:

https://github.com/catalogueglobal/datatools-ui/blob/42211585c070484fe57ce188c2f0049378486cb7/lib/manager/actions/status.js#L123-L180