Update container (and a couple other) icons

[abey79]

What

#4663 introduced a bunch of new icons, but the container icons were a tad too busy. This PR introduce the new version from @martenbjork, along with a couple other minor icon tweaks.

New icons:

In the UI:

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 newly built examples: app.rerun.io
  • Using examples from latest main build: app.rerun.io
  • Using full set of examples from nightly build: app.rerun.io
• The PR title and labels are set such as to maximize their usefulness for the next release's CHANGELOG

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