Make topbar responsive

• closes #662 (closed)
• closes #882 (closed)
• closes #883 (closed)
• closes #426 (closed)
• closes #991 (closed)

What does this MR do?

Updates the whole navigation topbar, so that is more responsive.

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

Navigation is important. Refactored a lot of code, so it is likely, that there might be a menu item which does not occur anymore, because I missed it.

Links to related issues

Any relevant links (issues, documentation, slack discussions).

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. Try out several screen sizes in following scenarios:
   • Not logged in.
   • Login as user1 (no foodsaver)
   • Login as user2 (foodsaver)
   • Login as bot (many rights)

Screenshots (if applicable)

ToDo

• Clean up some code snippets.
• Make right property in FsDropdownMenu accessable from outside.
• Make tests runnable again.
• Remove index.ts.
• Make sub menus more consistently.
• #883 (closed): Remove unused orga prop.
• Make Login translatable
• Add option to get to a forgot password?
• Add remember-me option (Compare branches) --> commit fe9fec4e

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

Die Navigationsleiste am oberen Rand wurde überarbeitet und ist jetzt responsive, also kann auf kleinen Displays besser dargestellt werden.