[WordPress] Suggest the Performance Lab plugin where applicable

[rviscomi]

A number of WordPress-specific audit messages include a link to the search results page at wordpress.org/plugins. Now that the WordPress Performance working group has built the Performance Lab plugin, I'd like to see Lighthouse making a more opinionated recommendation to use that specific plugin where applicable.

For example, the modern-image-formats audit has a WordPress stack pack message of:

Consider using a plugin or service that will automatically convert your uploaded images to the optimal formats.

The Performance Lab plugin promotes a module that does exactly that:

WebP Uploads: Creates WebP versions for new JPEG image uploads if supported by the server.

cc @adamsilverstein @felixarntz @ThierryA

[felixarntz]

@rviscomi I think that's a great idea. You're also right in that the modern-image-formats would be precisely the audit where that would probably make the most sense. Right now we don't yet have other modules in the plugin that directly address specific Lighthouse audits (most other modules are about providing "Site Health" diagnostics in the WP Admin UI).

What would it entail to add this recommendation for the modern-image-formats audit? I think we should start with that for now, and then as further modules land in the plugin that map to certain audits, we can expand.

[rviscomi]

It'd just entail a PR to modify this line:

lighthouse-stack-packs/packs/wordpress.js

Line 8 in 9344825

'modern-image-formats': "Consider using a [plugin](https://wordpress.org/plugins/search/convert+webp/) or service that will automatically convert your uploaded images to the optimal formats.",

[brendankenny]

PRs very welcome!

[ThierryA]

Excellent idea, I am very supportive of this indeed! I would also expect future recommendations to be added to other UIStrings as more modules are added to the Performance Lab plugin.