Hidden filters in a collapsible details element still display the summary

I ran into this exact problem. I'm upgrading all my facets blocks to native exposed filters in facets 3.0. The plan there is to lean heavily on this excellent configurable_views_filter_block module. I'm wanting to use collapsible bef filters and experienced the same thing in the IS.

I left a couple comments in the MR. There are a couple of if conditions that seem a bit off.

That said, the patch works for me and I'm going to use it. (Thanks, @mlncn!)

The concerns I have with the if conditions aren't going to affect my site. I do think the fix would be more robust if the conditions were modified slightly per my comments though.

Re-titled the issue as it seems we're all pretty specifically after BEF collapsible details element support in here.

MR 15 adds this support, taking a slightly different approach at the code level, hopefully making it easier to add support for additional filter wrappers in the future (should more requests like this come in) without repeating code.

Test coverage not added yet, so changing status back to needs-work.

Basic test coverage added in MR 15. Verifies the whole BEF filter wrapper is hidden when the exposed filter is configured not to show in a configurable views filter block. This is now ready for review.