Sort past polls new to old

What does this MR do?

Part of #975

• sorts past (expired) polls from new to old
• adds front-end filtering by name in vue, similar to forum threads
• fix the creation of polls for ambassadors ("Alle Botschafter aus dem Bezirk / der Gruppe") -> https://foodsharing.freshdesk.com/a/tickets/1308

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

Very sure. Part 1+2 are only in the front-end and cannot break any polls. Part 3 only fixes the creation of new polls.

How to test

Steps a reviewer can take to verify that this MR does what it says it does e.g.

1. Checkout branch locally
2. Login as foodsaver
3. Go to Göttingen -> Abstimmungen
4. Check the sorting of the past polls
5. Try filtering them by name

second bugfix:

1. Login as uservoting1
2. Go to Göttingen -> Abstimmungen
3. Create a new poll for the scope "ambassadors only" ("Alle Botschafter aus dem Bezirk / der Gruppe")
4. Login as userbot and check if you received a bell notification

Screenshots (if applicable)

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
• use "state:" labels to track this MR's state until it was beta tested
• added an entry to CHANGELOG.md
• add a short text that can be used in the release notes
• Once your MR has been merged, you are responsible to create a testing issue in Beta Testing Repo:
  • 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.

Release notes text

In der Liste von beendeten Abstimmungen stehen die neuesten Abstimmungen oben und die Liste lässt sich nach dem Namen einer Abstimmung durchsuchen.