refactor(portal): redo header

[TilmanHaupt]

Summary

Closes #398

PageHeader components leads to errors as breadcrumbs on the left are not supported, not as child and not in applicationName. Its reported as bug: cloudoperators/juno#1247

Testing Instructions

1. pnpm i
2. pnpm run test

Checklist

• I have performed a self-review of my code.
• I have commented my code, particularly in hard-to-understand areas.
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.
• I have made corresponding changes to the documentation (if applicable).
• My changes generate no new warnings or errors.