Support facets 3.x facets exposed filters

Support added in the 3505618-support-facets-exposed-filters branch. Tested against a variety of facet filters with a variety of employed coders, single and multi-value selections. Seems to be working well at this point.

Pretty paths coder config is at the filter-level (it shows in the exposed filter options form). It is possible to combine pretty and regular query string facet filters (eg. "/view/category/foo-258?tag=33).

Filter order in the URL is currently just following the filter order already established in the view.

Still needs test coverage and likely some additional refinement - both hopefully coming in this week.

Test coverage and small improvements added (some identified while adding the test coverage). This is now ready for review.

Attached is an immutable patch against 2.0.x representing the current state of the MR 20.

In testing I found that the pretty path redirect response to the views exposed form submission was coming back with "no-cache" in the cache control header. Adding cacheability metadata to the pretty path redirect response seems to have solved the issue. This should improve performance on previously-requested facet filter combinations.

Attached is an immutable patch against 2.0.x representing the current state of MR 20.

Tried this path, but it does not appear to be working, do I need to do anything?

It works great!! Thank you chrisolof!

c_archer you need to do the configuration of Facet Pretty Paths on the View that has the facets, in the Filter criteria section, presented as (for an 'example' facet name) "Facet: Example (example)" — you need to press that name to configure Pretty paths coder, not the Settings link as we all would usually expect.

Thanks mlncn, thats it working!

Just wondering when this will roll out?