Bell grouping

What does this MR do?

Generalizes the functionality of forum bells to be grouped and counted to reduce the number of (unnecessary) bells. With this MR more types of bells are grouped:

• Store wall posts
• Pickup time changes
• Store team requests

How confident are you it won't break things if deployed?

Quite confident, but this MR will cause some bells to be grouped and other not to be grouped while in beta - there seems no good way around that. Also, this MR can not be merged until the !3152 (merged) is in the prod version.

Checklist

• added a test, or explain why one is not needed/possible...
• no unrelated changes
• asked someone for a code review
• set a "for:" label to indicate who will be affected by this change
• added to the next milestone (see https://gitlab.com/foodsharing-dev/foodsharing/-/milestones, unless it has a "for:Dev" label)
• added an entry to CHANGELOG.md
• added a short text in the release notes to /release-notes/YYYY-MM.md
• Once your MR has been merged, you are responsible to create a testing issue in the Beta Testing forum: https://foodsharing.de/region?bid=734&sub=forum. Please change the MRs label to "state:Beta testing".
  • Consider writing a detailed description in German.
  • Describe in a few sentences, what should be tested from a user perspective.
  • Also mention different settings (e.g. different browsers, roles, ...) how this change can be tested.
  • Be aware, that also non technical people should understand.