Implement support for annotating certain plugins as experimental

[felixarntz]

Summary

Fixes #1045

Relevant technical choices

• Introduces a new perflab_get_standalone_plugin_data() function so that all standalone plugin data can be defined in one place.
  • I'm sure we wouldn't want to have to maintain the plugin list in two places, e.g. one for whether each plugin is experimental or not, and another one for each plugin's constant.
• Marks auto-sizes and embed-optimizer as experimental for now.
  • auto-sizes because its browser behavior isn't really available yet, embed-optimizer because it's very new and a 0.x version.
• Displays an "(experimental)" annotation on the feature card behind every plugin that is marked experimental.
• Displays the experimental plugins after all the non-experimental plugins.

See screenshot of what this would look like based on the PR implementation:

[github-actions]

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Co-authored-by: felixarntz <flixos90@git.wordpress.org>
Co-authored-by: mukeshpanchal27 <mukesh27@git.wordpress.org>
Co-authored-by: westonruter <westonruter@git.wordpress.org>
Co-authored-by: swissspidy <swissspidy@git.wordpress.org>

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[felixarntz]

Note for reviewers: I have opened this against release/3.0.0 since it's a technically relatively simple change which IMO would be great to include if we can get it across the finish line (we're still 1.5 weeks away from that release).

If there's substantial feedback or further discussion required that means this can't land in 3.0.0, we can adjust the base branch and change it to target 3.1.0.

[felixarntz]

Another note: The CI failures in https://github.com/WordPress/performance/actions/runs/8547642712/job/23420147133?pr=1111 are unrelated, so we should fix them separately. See #1012.

[mukeshpanchal27]

Thanks @felixarntz for the PR. It look good to me.

[mukeshpanchal27]

Another note: The CI failures in https://github.com/WordPress/performance/actions/runs/8547642712/job/23420147133?pr=1111 are unrelated, so we should fix them separately. See #1012.

The PR is #1112 not 1012

[swissspidy]

I was hoping we can just mark them as experimental based on the version number (i.e. < 1.0.0 is experimental), but turns out Auto Sizes is already at 1.0.0 🙃

[felixarntz]

@swissspidy

I was hoping we can just mark them as experimental based on the version number (i.e. < 1.0.0 is experimental), but turns out Auto Sizes is already at 1.0.0 🙃

Yeah, we probably need an extra flag. It's also worth considering that in certain edge-cases we may even want to designate plugins as experimental again when they weren't before. Potentially this could apply to Dominant Color Images / Image Placeholders as right now nobody is really exploring a path forward or maintaining it, and it received a lot of concerns/pushback when initially proposed in a Make Core post. Just thinking out loud, I'm not saying we should do that. But probably a flag is helpful for several reasons.

Could you (or someone else) please give another review to this PR? Since #1112 was now merged into this, the CI failures are resolved, so this is good for a review.

[felixarntz]

Note for reviewers: This function is simply moved down (see bottom of the file), it's not being replaced as potentially the diff here may suggest.

[westonruter]

LGTM but with a suggestion to formalize the description of a return value with an array shape for static analysis.