feat(CreateApp): Code cleanup and make the CreateAppForm accessible

[framitdavid]

Description

This pull request (PR) addresses issue #11475 and has undergone code refactoring to enhance readability and improve the accessibility of the feature.

Related Issue(s)

• NewApp: Create and Cancel button overflows information. #11475

Verification

• Your code builds clean without any errors or warnings
• Manual testing done (required)
• Relevant automated test added (if you find this hard, leave it and we'll help out)
• Cypress tests run green locally (https://github.com/Altinn/altinn-studio/tree/master/frontend/testing/cypress#run-altinn-studio-tests)

Documentation

• User documentation is updated with a separate linked PR in altinn-studio-docs. (if applicable)

[codecov]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (3ef5edc) 83.70% compared to head (9271e17) 83.70%.
Report is 3 commits behind head on master.

Files	Patch %	Lines
...nd/dashboard/pages/CreateService/CreateService.tsx	94.28%	0 Missing and 2 partials ⚠️
...ents/ServiceOwnerSelector/ServiceOwnerSelector.tsx	94.11%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #11496   +/-   ##
=======================================
  Coverage   83.70%   83.70%           
=======================================
  Files         883      885    +2     
  Lines       13052    13050    -2     
  Branches     1711     1712    +1     
=======================================
- Hits        10925    10924    -1     
+ Misses       1868     1866    -2     
- Partials      259      260    +1     

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[TomasEng]

Fremragende arbeid. Dette ble mye ryddigere! Har bare noen forslag til den nye hooken.

[nkylstad]

Result looks good in dev! Moving to "Done"