Add option to show current search string in facet summary

I extended the patch from #2979223-57: Add option to show current search string in facet summary → with the fix from 🐛 Facets with ajax enabled and no source path results in /views/ajax?f... urls RTBC

FWIW I'm using this patch on a client site and it's working fine, but the client has requested exploded (individual) search terms rather than the whole search string, so one at a time can be cleared. This may be a use case others have as well. For now as a front-end dev I'm just going to have to go a different route and create the functionality with JS, but might be worth considering this as a config option.

Patch contains deprecated getMasterRequest. Rewritten to getMainRequest.

Created branch 2979223-search-string-summary from 3.0.x and re-rolled the patch from https://www.drupal.org/project/facets/issues/2979223#comment-15146318 ✨ Add option to show current search string in facet summary Needs work

I'm not sure that I should change the version of this issue to 3.0.x-dev, though, so I'll leave that for others to decide.

The reset facets option ("Adds reset facets link") will be shown now as well when a search query is used.

This is marked as NW for 2 years. Why don't we get brave and ask for a review?

It should also see a re-roll for 3.x though, so maybe NW is accurate?

heddn → changed the visibility of the branch 2979223-search-string-summary-v2 to hidden.

heddn → changed the visibility of the branch 3.0.x to hidden.

NW because tests are failing (the first few failures look simple to fix) and phpc/phpstan complaints.

Updated patch

Looks like the auto merge train didn't actually merge this. What more work is needed here?