Rewriting data model (schema + data) fetching to Tanstack Query

[olemartinorg]

Description

While working on extending the feedback.ts test for the stateless test-app, I found that it failed to properly fetch the json schema for a new data model I added to the app. After a trip down a rabbit hole and back, I've refactored and rewritten the logic to fetch both the data model schema and current data using Tanstack Query instead of legacy Redux Sagas. It fixed the problem I had in the stateless app, so I was able to continue working on extending those tests.

Related Issue(s)

• Experiment: Storing the data model in a Context #1175

Verification/QA

• Manual functionality testing
  • I have tested these changes manually
  • Creator of the original issue (or service owner) has been contacted for manual testing (or will be contacted when released in alpha)
  • No testing done/necessary
• Automated tests
  • Unit test(s) have been added/updated
  • Cypress E2E test(s) have been added/updated
  • No automatic tests are needed here (no functional changes/additions)
  • I want someone to help me make some tests
• UU/WCAG (follow these guidelines until we have our own)
  • I have tested with a screen reader/keyboard navigation/automated wcag validator
  • No testing done/necessary (no DOM/visual changes)
  • I want someone to help me perform accessibility testing
• User documentation @ altinn-studio-docs
  • Has been added/updated
  • No functionality has been changed/added, so no documentation is needed
  • I will do that later/have created an issue
• Support in Altinn Studio
  • Issue(s) created for support in Studio
  • This change/feature does not require any changes to Altinn Studio
• Sprint board
  • The original issue (or this PR itself) has been added to the Team Apps project and to the current sprint board
  • I don't have permissions to do that, please help me out
• Labels
  • I have added a kind/* label to this PR for proper release notes grouping
  • I don't have permissions to add labels, please help me out

[sonarqubecloud]

SonarCloud Quality Gate failed.   

1 Bug
0 Vulnerabilities
0 Security Hotspots
7 Code Smells

23.3% Coverage
0.0% Duplication

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