Need to support fabric-scoped commands

[bzbarsky-apple]

We need to be able to mark commands as fabric-scoped in the XML.

The relevant pieces are:

1. Have isFabricScoped="true" in the XML on the relevant commands.
2. Add a field to the COMMAND table to store the value (similar to MUST_USE_TIMED_INVOKE).
3. Fix XML import to set the COMMAND field based on the XML.
4. Allow some way to do things with fabric-scoped commands via helpers. Either expose the state in the data zcl_commands fetches, or have a custom helper like zcl_commands_that_need_timed_invoke; no really strong opinions here, though the zcl_commands approach seems a bit more flexible.