[Manual Backport 2.x] Feat (core): Make theme settings user-specific and user-configurable (#5652)

[ananzh]

Backport PR:

#5652

Description

• feat (core): make theme UI settings client-side

1. Add optional preferBrowserSetting to UISettings that should be defined client-side
2. Make theme:darkMode and theme:version prefer browser settings
3. Update UISettings client-side client to check localstorage for settings that prefer browser settings
4. Refactor logos to be responsive to browser-defined theme mode
5. Add a new startup script that handles theme/dark mode (injected as blocking script to head)
6. Remove theme/mode-specific logic from injected Styles and Fonts (move logic to startup script instead, define all font-faces)
7. Only inject theme values necessary for loading/error screens via startup
8. Update branding metadata to pass the correct dark mode
9. Add a new control for admin Enable user control. This setting is enabled as default. When this setting is disabled, admin can disable any user control and we will have the exact previous behavior.

Check List

• All tests pass
  • yarn test:jest
  • yarn test:jest_integration
• New functionality includes testing.
• New functionality has been documented.
• Update CHANGELOG.md
• Commits are signed per the DCO using --signoff

[codecov]

Codecov Report

Attention: Patch coverage is 22.41379% with 90 lines in your changes are missing coverage. Please review.

Project coverage is 67.75%. Comparing base (fcc06de) to head (7fb52a4).

Files	Patch %	Lines
...dvanced_settings/public/header_user_theme_menu.tsx	2.43%	40 Missing ⚠️
src/core/public/ui_settings/ui_settings_client.ts	13.63%	16 Missing and 3 partials ⚠️
src/legacy/ui/ui_render/ui_render_mixin.js	0.00%	18 Missing ⚠️
src/core/server/rendering/rendering_service.tsx	50.00%	0 Missing and 3 partials ⚠️
src/plugins/advanced_settings/public/plugin.ts	0.00%	3 Missing ⚠️
.../advanced_settings/public/register_nav_control.tsx	0.00%	3 Missing ⚠️
...s/public/management_app/components/field/field.tsx	75.00%	1 Missing and 1 partial ⚠️
src/core/public/osd_bootstrap.ts	66.66%	0 Missing and 1 partial ⚠️
...gs/public/management_app/lib/to_editable_config.ts	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              2.x    #6681      +/-   ##
==========================================
- Coverage   67.82%   67.75%   -0.08%     
==========================================
  Files        3410     3411       +1     
  Lines       66751    66814      +63     
  Branches    10842    10849       +7     
==========================================
- Hits        45277    45270       -7     
- Misses      18840    18907      +67     
- Partials     2634     2637       +3     

Flag	Coverage Δ
Linux_1	33.19% <5.26%> (-0.01%)	⬇️
Linux_2	55.64% <25.42%> (-0.08%)	⬇️
Linux_3	45.26% <18.75%> (-0.01%)	⬇️
Linux_4	35.02% <8.24%> (-0.05%)	⬇️
Windows_1	33.21% <5.26%> (-0.01%)	⬇️
Windows_2	55.60% <25.42%> (-0.08%)	⬇️
Windows_3	45.26% <18.75%> (-0.01%)	⬇️
Windows_4	35.02% <8.24%> (-0.05%)	⬇️

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