Showing validation error in vscode when using invalid IDs for components

[olemartinorg]

Description

As proven in #734, ending a component ID with -5 (or any <dash><number>) may cause trouble. Since we add state like that when components are used inside repeating groups, weird stuff will happen if you provide those kinds of IDs yourself. Since it's a very large undertaking to fix this problem in app-frontend right now, we should at least warn developers about this when they edit their layouts in vscode.

Related Issue(s)

• closes Dynamics repeating groups error #734

Verification

• Manual testing
  • I have tested these changes manually
  • Creator of the original issue (or service owner) has been contacted for manual testing
  • No testing done/necessary
• Automated tests
  • Unit test(s) have been added
  • Cypress E2E test(s) have been added
  • No automatic tests are needed here
  • I want someone to help me make some tests
• User documentation @ altinn-studio-docs
  • Has been updated
  • No changes/updates needed
• Changes/additions to component properties
  • Changes are reflected in both layout/index.ts and layout.schema.v1.json, and these are all backwards-compatible
  • No changes made
• 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