This change considers all existing search areas in Moodle and makes
necessary changes.
Custom change to course search, supported by helper in base.php:
* course/classes/search/mycourse.php
Custom change to message search:
* message/classes/search/message_received.php
* message/classes/search/message_sent.php
Custom change to user search:
* user/classes/search/user.php
Custom changes to module areas, supported by helper in base_mod.php:
* mod/book/classes/search/chapter.php
* mod/data/classes/search/entry.php
* mod/forum/classes/search/post.php
* mod/glossary/classes/search/entry.php
* mod/survey/classes/search/activity.php
* mod/wiki/classes/search/collaborative_page.php
(Note: the unit tests do not exhaustively check every context type
for these, given that's mainly handled by the helper function
which was already tested in the base_activity test.)
Handled by block base class (no change):
* blocks/html/classes/search/content.php
Handled by activity base class (no change):
* mod/assign/classes/search/activity.php
* mod/book/classes/search/activity.php
* mod/chat/classes/search/activity.php
* mod/choice/classes/search/activity.php
* mod/data/classes/search/activity.php
* mod/feedback/classes/search/activity.php
* mod/folder/classes/search/activity.php
* mod/forum/classes/search/activity.php
* mod/glossary/classes/search/activity.php
* mod/imscp/classes/search/activity.php
* mod/label/classes/search/activity.php
* mod/lesson/classes/search/activity.php
* mod/lti/classes/search/activity.php
* mod/page/classes/search/activity.php
* mod/quiz/classes/search/activity.php
* mod/resource/classes/search/activity.php
* mod/scorm/classes/search/activity.php
* mod/url/classes/search/activity.php
* mod/wiki/classes/search/activity.php
* mod/workshop/classes/search/activity.php
