11360 cleanup error message components

[JamalAlabdullah]

Description

Added a reusable StudioPageError component to @Studio/components to use it instead of different error types. This component will return the alert from the design system.

Changes:

• Added a test file.
• Added a CSS file.
• Added StudioPageError.stories.tsx.
• Added StudioPageError.mdx.
• Removed the old ErrorPage component along with its related index and CSS files because it has been replaced with
  StudioPageError.
• Reused StudioPageError in relevant places.

Related Issue(s)

• Cleanup error message components #11360

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)

Documentation

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

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.62%. Comparing base (a7b02a2) to head (d3020e0).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #13237   +/-   ##
=======================================
  Coverage   93.61%   93.62%           
=======================================
  Files        1423     1421    -2     
  Lines       19815    19803   -12     
  Branches     2402     2402           
=======================================
- Hits        18550    18540   -10     
+ Misses       1015     1013    -2     
  Partials      250      250           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[TomasEng]

Denne branchen henger litt etter master nå. Kan du oppdatere den, @JamalAlabdullah?

[JamalAlabdullah]

Denne branchen henger litt etter master nå. Kan du oppdatere den, @JamalAlabdullah?

Oppdatert nå 👍

[TomasEng]

Fin opprydning.

[TomasEng]

Utmerket!