Target the overall metric with `*` and any intent or entity with `**`

[rozele]

Currently, we only have an option to target the overall intent or entity metric using *. Users may want the option to apply the threshold against all intents or entities. We could use ** to represent this.

[rozele]

Not sure this is the best idea given intents and entity types change over time. Likely it's better to explicitly call out the intent or entity type for each.