(bug 56018) add descriptions to entity search text

This also splits the search text generation into a separate class
and improves tests.

Change-Id: I08c9f5d10c83506cb540cc4c0c872e8958fa5a85
Include site link page names in search index text

Change-Id: I7b3b2443f651f7add62b52390a29a5d89f46c7b2
Merge changes I7b3b2443,I08c9f5d1

* changes:
  Include site link page names in search index text
  (bug 56018) add descriptions to entity search text