Allow trigger groups to have an ID

[karwosts]

Recently I added the concept of trigger groups (home-assistant/core#117698), to allow blueprint writers to have a way to use one or more trigger selectors with their blueprints, so that we have a way to merge nested lists of triggers.

This is useful but it does have a limitation, that when an automation is triggered, the automation cannot determine from which group of triggers a trigger initiated from.

So if the blueprint has two selectors, call them "A triggers" and "B triggers", users can add multiple triggers to both sets, e,g.

blueprint:
  input:
    a_triggers:
      name: "Triggers to do something"
      default: []
      selector:
        trigger:
    b_triggers:
      name: "Triggers to do something else"
      default: []
      selector:
        trigger:
        
triggers:
  - triggers: !input a_triggers
  - triggers: !input b_triggers

action:
  ...        

But when a particular trigger fires, there's no way to identify if that trigger was from the A group or the B group.

I would like to have a way to identify this, and I had the idea that triggers could also have an id added to it, e.g.:

triggers:
  - triggers: !input a_triggers
    id: a_trigger_group
  - triggers: !input b_triggers
    id: b_trigger_group

This could either do one of two things (I haven't decided):

1. All the flattened triggers would automatically inherit the trigger id from the group. So any triggers added to a_triggers would have a trigger.id of "a_trigger_group". Any trigger_id manually added to the individual triggers by the end user would be thrown away.

or

2. All the flattened triggers would get a new property trigger.group_id equal to "a_trigger_group". Any trigger_id manually added to individual triggers would continue to exist, so a trigger could have both an trigger.id and a trigger.group_id.

Option 2 seems slightly more flexible, but also maybe needlessly overcomplicated. In theory both could be used if a blueprint also had an action selector or condition selector, and end-user also added a manual trigger id to a trigger, and checked for the existence of that id in a manual action or condition.

Is either one of these options preferred or would be accepted?