Searching for falsy values (ie 0) doesn't work

[Xon]

Affected version

2.2.11

There are a number of places which search_query doesn't do strict equality checks, and keyword handling when plumbing into the Query entity doesn't do it either.

Additionally; XF\Pub\Route\Search::build probably should just add the various XF\Entity\Search attributes without an empty-query check since by that stage those checks have been done everywhere else.