Replace the "Options" submenu with a settings screen

[abey79]

What

This PR:

• removes the Options submenu and replace it with a full-window "Settings" screen
• moves the Restart with WebGPU/WebGL menu item to the top-level in the rerun menu (wasm only)
• add a field for the Mapbox access token in the settings
• fixes Add a global setting to set a mapbox access token #7849

Web viewer:

Checklist

• I have read and agree to Contributor Guide and the Code of Conduct
• I've included a screenshot or gif (if applicable)
• I have tested the web demo (if applicable):
  • Using examples from latest main build: rerun.io/viewer
  • Using full set of examples from nightly build: rerun.io/viewer
• The PR title and labels are set such as to maximize their usefulness for the next release's CHANGELOG
• If applicable, add a new check to the release checklist!
• If have noted any breaking changes to the log API in CHANGELOG.md and the migration guide

• PR Build Summary
• Recent benchmark results
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[Wumpf]

looking great!