Expose which search strategy produced each result

query_packages now assigns @search_sources - a hash mapping package
ids to the matching strategy that put them into the results: :exact,
:name_prefix, :name_contains, :semantic or :fulltext. The grid and
list views render a small badge with a humanized label per result,
making the search tiers observable. semantic_results() was folded
into search_packages() so each branch tags its own source. Adds the
rails-controller-testing gem for assigns() in tests.

app/views/packages/browse.slim

@@ -24,6 +24,9 @@
                   = pkg.name
                 .text
                   = pkg.description
+                - if @search_sources[pkg.id]
+                  .text.search-source
+                    span.label.secondary = search_source_label(@search_sources[pkg.id])
       - elsif @view_style==:list
         - @packages.to_a.each do |pkg|
           .grid-x.grid-margin-x.listview
@@ -37,6 +40,9 @@
                 a href=package_path(name: pkg.name)
                   =pkg.name
               p =pkg.description
+              - if @search_sources[pkg.id]
+                p
+                  span.label.secondary = search_source_label(@search_sources[pkg.id])
               .listview.longdescription
                 = pkg.long_description_first_paragraph