MDL-47875 choice: chat module strings not required from Choice anymore

AMOS BEGIN
 CPY [chatintro,mod_chat],[description,mod_choice]
AMOS END
Merge branch 'MDL-47875_master' of https://github.com/crazyserver/moodle
MDL-47959 mod_quiz: fixed 0 questions bug
MDL-47919 tool_monitor: only use set_label() on valid object
on-demand release 2.8beta+
MDL-47983 tool_monitor: Removing only-for-admins restriction