Fix VisualizerOverrides serializer and improved error handling

[jleibs]

What

• Resolves: VisualizerOverrides broken likely due to same old serialization issue #7287

The field-converter ended up misnamed likely during a component type refactor.

• Add new unit-test for the specific case
• Add new check for valid field converts.
• Fix the field converter itself
• Add a release checklist that uses the override functionality.

Also if VisualizerOverrides is bad, we now handle it more gracefully instead of spamming warnings.

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

To run all checks from main, comment on the PR with @rerun-bot full-check.

[teh-cmc]

This does not seem to fix the plot:

• https://rerun.io/viewer/pr/7288?url=https%3A%2F%2Fapp.rerun.io%2Fversion%2Fnightly%2Fexamples%2Fplots.rrd
  

[jleibs]

The bug was in serialization. The old rrd still has the wrong data. This worked for me when running locally.

[teh-cmc]

The bug was in serialization. The old rrd still has the wrong data. This worked for me when running locally.

Ha! right