Duplicate facets on a sidebar with widgets in it

[modelm]

As implemented, search facets assume (and only work with) an empty sidebar. If there are widgets in the target sidebar, facets are duplicated (and probably break in other ways, not thoroughly tested). Make facets portable to ensure compatibility regardless of theme or other widgets.

This will involve replacing at least the following:

• https://github.com/mlaa/elasticpress-buddypress/blob/master/features/buddypress/buddypress.php#L45
• https://github.com/mlaa/elasticpress-buddypress/blob/master/features/buddypress/facets.php#L136

Probably best to turn this into a widget and make it optional to include on the search sidebar?

[modelm]

Use https://www.elasticpress.io/blog/2018/04/elasticpress-2-5-facets/ and replace existing facet widget.