New hook CheckUserInsertForRecentChange

Allow extensions to adjust the data inserted to cu_changes for RecentChange rows.
Some extensions store additional data in rc_params which is not inserted to the
cu_changes table.  This gives those extensions a chance to adjust the insert so
all necessary data is included.

Bug: 60559
Bug: 61927
Change-Id: I4b4a4f3855f2aaa92b5bad84a8e444cdbaf9a1af
Merge "New hook CheckUserInsertForRecentChange"