Implement usual hover and selection interactions in the map view

[abey79]

What

This PR adds the "usual" UI interactions to the map view, including:

• hover highlight
• click to select instance
• cmd-click to add instance to selection
• double-click to select entire entity
• click anywhere else in the map view to select the view
• hover tooltip for the instances

Note: the rendering of the selection/hover silhouette requires a whole bunch of draw passes, which clearly highlights (pun not intended) the need to eventually transit to using re_renderer.

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
• Wasm size tracking

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