Ability to define sub labels to be classified as an alert.

Describe what you are trying to accomplish and why in non technical terms

I want to be able to configure Frigate such that only sub labels of car (Amazon, FedEx, etc.) create alerts.

Additional context

This will be fairly straightforward by having a sub_labels field under alerts next to labels. Then a user could remove car from the labels and only include specific sub_labels to be considered for review.

This will also require some sort of API which accumulates sub labels across features such as Frigate+ / custom models, face recognition, LPR, and object classification.

NOTE: This only applies to alerts, an accompanying field for detections would require downgrading alerts which is not viable.