Show the worker activity state in the process status view

https://redmine.teklia.com/issues/8918

When viewing the status of a Workers process only, a new Worker activities field should be included in the list of fields. This field shows the value of Process.activity_state using a new PROCESS_ACTIVITY_STATES constant in src/config.ts: Disabled, Pending, Ready, Error.

This field does not need to be included for any process other than Workers processes since we current do not support activities in other modes.

Please make sure that this field gets properly updated by the existing automatic refresh, like the other fields. This can be quickly tested by manually editing the value on a process in a shell or the admin while having the process open on another page; the field should update automagically after a few seconds.