Show outline around hovered/selected tiles in viewport

[emilk]

What

• Builds upon and merges into Make object hover & selection colors brighter and more pronounced #6596
• Closes Selecting vertical/horizontal/grid containers within a vertical/horizontal/grid container should draw a box when selected #5174

tile-highlight-2.mp4

Checklist

• I have read and agree to Contributor Guide and the Code of Conduct
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• 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
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[jprochazk]

Nice!