Add userdata backend functionality

[MaHaWo]

• add models for answers to user questions
• adds endpoints for put and get requests. No full CRUD because not required afais
• adds tests
• adjusts frontend respectively. Because the backend user questions part is not fully functional atm and a fix would have increased complexity and extend of this PR significantly, this currently still uses the hardcoded questions from the frontend page and translates them into the correct structure. This incurs a certain amount of temporary logic to do so, which will go once the admin backend is fixed (next task).
• adds translations where necessary. user questions are not translated b/c the aforementioned problem.
• add required and disabled fields where necessary
• there's still a lot of debug output in there that will go with the next PR probably
• stupid hack for making the page rerender: `data = [...data] because of svelte<4 not tracking nested references for rerendering. svelte 5 runes to the rescue?
• the SQLModel models can perhaps be improved, I got a little confused about when and how the database index is added and wanted to get this to a functional state asap with the idea that it might change again, so the primary key and the question_id are currently separate, even though the could be the same functionally.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 16.84783% with 153 lines in your changes missing coverage. Please review.

Project coverage is 17.48%. Comparing base (2daf248) to head (2168992).

Files with missing lines	Patch %	Lines
frontend/src/lib/components/UserDataInput.svelte	0.00%	97 Missing :warning:
frontend/src/lib/client/schemas.gen.ts	0.00%	20 Missing :warning:
frontend/src/lib/client/services.gen.ts	0.00%	18 Missing :warning:
...d/src/routes/userLand/userLandingpage/+page.svelte	0.00%	12 Missing :warning:
...tend/src/lib/components/DataInput/RadioList.svelte	0.00%	4 Missing :warning:
...tend/src/lib/components/DataInput/DataInput.svelte	0.00%	1 Missing :warning:
mondey_backend/src/mondey_backend/routers/users.py	95.45%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #118 +/- ## ========================================== + Coverage 17.22% 17.48% +0.25% ========================================== Files 98 98 Lines 4974 5078 +104 Branches 125 125 ========================================== + Hits 857 888 +31 - Misses 4047 4120 +73 Partials 70 70 ```

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[sonarcloud[bot]]

Quality Gate passed

Issues
2 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud