Replace placeholder alarm schema

[dplute21]

This replaces the placeholder alarmset block with an initial design for real alarm data.

The alarmset section follows much of the same general flow as pointset:

1. Discovery events provide details about the alarm definitions associated with a piece of equipment, including:
   • Reference name
   • Display name
   • Description (e.g. to off-normal text)
   • Category (arbitrary, defined by the client platform)
   • Severity (arbitrary, defined by the client platform)
   • Does it require acknowledgement?
   • Does it return to normal?
   • Does returning to normal require acknowledgement?
2. An external mapping process produces a list of normalized alarm names and their corresponding reference names.
3. Config messages provide the client with the authoritative list of alarms to observe and report.
4. Alarmset events are sent when a configured alarm is triggered, acknowledged, or returns to normal. Event details include:
   • Activation time
   • Activation acknowledgement details (time, user, comment)
   • Is the alarm currently active?
   • Return-to-normal time
   • Return acknowledgement details (time, user, comment)