Decoupling commit and notification template

[tun0]

Would it be an option to decouple the commit message template and the notification template? Where the latter would have access to git commit specific data as well (sha specifically).

Instead of fully decoupling, alternatively it could be made possible to have an additional template for stuff to add to the notification, in addition to the commit template.

End goal: have more control over the notification payload to make it machine parsable (even) more reliably.

Originally posted by @tun0 in #580 (comment)