[ticket/12523] Add template events search_results_topic_(before/after)

Add template events search_results_topic_(before/after)
to search_results.html.

PHPBB3-12523
Merge pull request #2436 from rxu/ticket/12523

[ticket/12523] Add template events search_results_topic_(before/after)

* rxu/ticket/12523:
  [ticket/12523] Add template events search_results_topic_(before/after)