Search page refactor

[jamiefeiss]

The search page now uses the new search implementation outlined in RDFLib/prez#149.

Users can filter by a base class, containers, and can provide custom inbound & outbound filters.

Resolves #95, resolves #72.

[recalcitrantsupplant]

I've tested locally, looks good, only one minor issue:
As the current backend MVP search doesn't allow UNION across different filter conditions, rather it's an AND, if a user tries to search in two kinds of Container class, most likely results do not exist as instances of both Container class, so they'll get no results. For example restricting to search within datasets only yields a result:

Searching within a dataset and a vocabulary yields no result:

The assumption here is a user would expect when ticking multiple Container instances, results can come from within any instance, not that the result must exist in all of them.

I'd make the following recommendations for non-MVP enhancements:

• tick all Container options and Containers by default - or have a special "select all" option at the top so it's clear everything is searched by default. When the query is sent to the backend, if it's a "select all" then the filter could be left off altogether, I think you've previously suggested this.
• Make it clear which label properties/predicates are being searched. At present this is label, description, and provenance (yes, the backend still needs to expose this information ..)
• Display the object class using a label rather than URI
• Presumably searching within a Container should include all objects that are transitively within it - e.g. Features within a Dataset - something for us to discuss tomorrow. We'd need to update the backend to support this first though.

[recalcitrantsupplant]

see comments above

[jamiefeiss]

@recalcitrantsupplant thanks for the comments. What changes would you suggest for this MVP now? I could start by adding to the page that you can't select multiple container types.

[recalcitrantsupplant]

Just the one to restrict searching to one container type at present

[jamiefeiss]

Added pagination using RDFLib/prez#159