Before the patch, queries like:

SELECT 1 FROM dual UNION SELECT 2 FROM dual

were failing badly, with everything but the first numeric element
being ignored by the optimization.

So, being conservative, now we reduce the query being analysed,
ignoring any subquery, inline view (anything within parenthesis
in general) and, in the remaining query, if a boolean query (UNION,
MINUS, INTERSECT...) is found, we don't apply any optimization.

* Pass $forcehttps parameter to call extract_draft_file_urls_from_text()
 call in \core_weblib_testcase::test_extract_draft_file_urls_from_text()
* Style fixes

This also makes message_sent::create_from_ids() $courseid
parameter required.