Change the way free-text queries are handled in SCEA

[ke4]

Currently, if user submits a free-text query (rather than selecting an auto-suggested term from either the Gene or Metadata categories) it is interpreted by the search pipeline as a gene search. This assumption is no longer valid and we need to change the way free-text queries are handled as follows:

• full gene and metadata search for free-text queries should be performed
• both sets of results displayed in separate tabs on the results page (this would echo the baseline/differential result tabs we have in bulk Atlas) and if both have results, Cell type (~metadata) results shown first
• if only one type of search (the metadata or the gene search) yields any results then I think we should either show just the one tab or both tabs but the empty one being second/'hidden' with the message 'no results found' displayed or something like that (so the tab with results is shown first by default)

So the results page for a free-text query that gives results for both metadata search and gene search (e.g. 'gut') would look something like this (with the metadata ~ cell type results tab shown first by default - if it has results, otherwise if only gene search has any results show that first/only as described above) and users can switch to the gene search results if what they were looking for was actually a gene or gene symbol):

As discussed with Alfonso, Pablo and developers this 'dual search' is not expected to put too much strain on the system that could result in time-outs or page loading issues on SCEA. However Pablo noted that this should be implemented AFTER Karoly's finished his work on streamlining (paginating??) the gene search and results, which is the more intensive of the two search types