Notification schema doesn't include Override details

[slominskir]

The Notification message currently only contains a list of override names:

https://github.com/JeffersonLab/jaws-libp/blob/22fe5ed50483df574be2447bab418e8e450c475e/src/jaws_libp/avro/schemas/EffectiveNotification.avsc

The admin GUI at least needs to know the details of the override (like the comments). This means a separate subscription to the alarm-overrides topic must be used. Might make sense to include the details in the Notification message.