[PUI] Dashboard refactor

[SchrodingersGat]

This PR presents a major refactor of the "dashboard" feature in PUI, bringing it closer towards a release state.

We were already using react-grid-layout for the new dashboard - this PR moves the implementation forward, adding new features, refactoring, etc

Main Goals

• Remove duplicate "home" / "dashboard" pages
• Improve usability of dashboard
• Add method of "adding" new widgets to the dashboard
• Add method of "removing" widgets from the dashboard
• Replicate all previous "home page" functions as "dashboard" items
• Provide a library of "builtin" dashboard items
• Save and restore separate layout "per user"
• Allow plugins to register dashboard items
• Cleanup global navigation menu (left-hand drawer)
• Playwright tests
• Consolidate UI plugin API settings
• Single entrypoint for accessing UI features on backend
• Update documentation

Screenshots

Description	Image
Sample dashboard with builtin items, and items loaded via plugins
Add new item
Remove Items
Adjust layout

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.36%. Comparing base (48dd3d3) to head (47182da).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8278      +/-   ##
==========================================
+ Coverage   84.28%   84.36%   +0.07%     
==========================================
  Files        1165     1164       -1     
  Lines       52770    52476     -294     
  Branches     1931     1895      -36     
==========================================
- Hits        44478    44269     -209     
+ Misses       7808     7730      -78     
+ Partials      484      477       -7     

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