Add visibility: and is:sensitive filters

app/lib/search_query_transformer.rb

@@ -112,7 +112,7 @@ class SearchQueryTransformer < Parslet::Transform
       end
 
       case prefix
-      when 'domain', 'is', 'has', 'lang'
+      when 'domain', 'is', 'has', 'lang', 'visibility'
         @filter = prefix.to_s
         @term = term
       when 'from'

app/models/status.rb

@@ -179,6 +179,7 @@ class Status < ApplicationRecord
     keywords << :local if local?
     keywords << :local_only if local_only
     keywords << :reply if reply?
+    keywords << :sensitive if sensitive?
     keywords
   end