Add indicator lights for capture agent status

The capture agent table in Capture / Locations should have indicator lights to improve usability and situational awareness of Opencast system managers and support staff.

As per the Admin UI style guide, Alerts and Indicators:

https://docs.opencast.org/develop/developer/modules/admin-ui/style/alerts-indicators/

Mapping to CA states:

IDLE: Green
SHUTTING_DOWN: Yellow
CAPTURING: Blue
UPLOADING: Blue
ERROR: Yellow
UNKNOWN: Yellow
OFFLINE: Red