Refactor data input element (again)

[MaHaWo]

• add custom RadioList component with support for single or multiple value input
• remove weird behavior when having additional values provided through a textbox. the additional stuff lives in a separate variable now.
• integrate RadioList into ChildRegistration and UserRegistration pages. Make things with less than five elements RadioList, data input elements with more I left as dropdowns because I found it visually overwhelming.
• make ChildrenRegistration and UserRegistration the same since they do the same thing
  Question: Should they be Modal perhaps?
• move all the data definitions into the respective +page.svelte from the component svelte files.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 339 lines in your changes missing coverage. Please review.

Project coverage is 18.10%. Comparing base (c12c462) to head (908718a).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
...d/src/routes/childLand/childDataInput/+page.svelte	0.00%	114 Missing ⚠️
...end/src/routes/userLand/userDataInput/+page.svelte	0.00%	85 Missing and 1 partial ⚠️
.../src/routes/userLand/userRegistration/+page.svelte	0.00%	36 Missing and 1 partial ⚠️
...end/src/lib/components/ChildrenRegistration.svelte	0.00%	20 Missing ⚠️
frontend/src/lib/components/UserDataInput.svelte	0.00%	18 Missing ⚠️
...tend/src/lib/components/DataInput/DataInput.svelte	0.00%	16 Missing ⚠️
...end/src/lib/components/DataInput/Fileupload.svelte	0.00%	11 Missing and 1 partial ⚠️
...tend/src/lib/components/DataInput/RadioList.svelte	0.00%	11 Missing and 1 partial ⚠️
...rontend/src/routes/userLand/userLogin/+page.svelte	0.00%	11 Missing ⚠️
...rontend/src/lib/components/UserRegistration.svelte	0.00%	8 Missing ⚠️
... and 2 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #73      +/-   ##
==========================================
- Coverage   18.38%   18.10%   -0.29%     
==========================================
  Files          73       75       +2     
  Lines        3067     3116      +49     
  Branches      106      108       +2     
==========================================
  Hits          564      564              
- Misses       2450     2497      +47     
- Partials       53       55       +2     

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[MaHaWo]

@lkeegan you want to have another look?

[sonarcloud]

Quality Gate passed

Issues
0 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

[lkeegan]

lgtm - as discussed I'll try to construct the JSON that the backend will provide, then we can revisit this