feat: add page header component with user menu

[mszekiel]

Related Issue or Design Document

Checklist

• I have read the contributing guidelines and signed the CLA.
• I have referenced an issue containing the design document if my change introduces a new feature.
• I have read the security policy.
• I confirm that this pull request does not address a security vulnerability.
  If this pull request addresses a security vulnerability,
  I confirm that I got approval (please contact [email protected]) from the maintainers to push the changes.
• I have added tests that prove my fix is effective or that my feature works.
• I have added the necessary documentation within the code base (if appropriate).

Further comments

[codecov]

Codecov Report

Attention: Patch coverage is 71.95122% with 23 lines in your changes missing coverage. Please review.

Project coverage is 51.91%. Comparing base (a2a032e) to head (f068a2b).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...eact/src/theme/default/components/ui/user-menu.tsx	52.63%	9 Missing ⚠️
.../src/theme/default/components/ui/dropdown-menu.tsx	75.00%	6 Missing ⚠️
...c/theme/default/components/generic/page-header.tsx	50.00%	3 Missing ⚠️
...ments-react/src/components/generic/page-header.tsx	50.00%	2 Missing ⚠️
...ct/src/theme/default/components/ui/user-avater.tsx	66.66%	2 Missing ⚠️
...ges/elements-react/src/theme/default/utils/user.ts	94.44%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #223      +/-   ##
==========================================
+ Coverage   50.05%   51.91%   +1.85%     
==========================================
  Files          94      103       +9     
  Lines         913      994      +81     
  Branches      115      122       +7     
==========================================
+ Hits          457      516      +59     
- Misses        452      473      +21     
- Partials        4        5       +1     

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