Send "New Silence" notification (trigger or list of fingerprints)

Could be useful to have the possibility of configuring get a notification when a new silence is created.
I spend a reasonable amount of time reading other issues, documentation, etc, and I couldn't find anything.

My use case

I'm deploying a new Prometheus and Alertmanager stack with notifications to Google Chat, to accomplish that currently i'm using mr-karan/calert. Meanwhile I'm developing (in my free time, just started) a Node.js proxy to send the notifications to the chat application by REST API.
The idea it's to grouping the alerts by the fingerprint to map them in a specific thread. I'm thinking of making a command in the bot, to create a new silence if it's called from a specific "alert thread", for example @Alertmanager silence

Given this, my idea it's to have a field in global configuration (or in the receivers), that allows send notification triggered by a new Silence created (maybe at expiration too), with the same fingerprint of the alert silenced (only if it available all the information to make the
required hash).
Another idea, a little bit easier I thinks, it's have the possibility of have custom fields in the silences or at least a list of fingerprints associated to the silence. Having this we could identify from the CLI, API etc, without having a trigger to accomplish this.

Other ideas, suggestions and further information in the configurations are welcome.
Regards.

The issue names no repository files or tests. Start by tracing silence creation through the CLI/API and the global configuration or receivers, then compare existing notification paths. Done would require a settled design and tests for the chosen new-silence notification, fingerprint list, or custom-field behavior.