Allow "Create new discussion for each group" to enable teachers to post the same question for each group with only one posting

Setup 1. Create a new course. 2. Create a teacher and multiple students (5-6 will do). 3. Enrol the teacher and students into the course. 4. Auto create 2 groups 5. Pick one of the students and enrol that student in both groups. Separate groups 1. In the course you just created, create a forum that has separate groups set as the Group Mode 2. Go to the "add a new discussion" form for the forum you just created. 3. Ensure that students are unable to see the "Post a copy to all groups" checkbox, and that teachers/admin can see the checkbox. Visible groups 1. Repeat the tests from the above section. No groups 1. Repeat the tests from the Separate Groups section. Ensure that in all cases, that the "Post a copy to all groups" checkbox does not display for any user. Behat 1. Run all behat tests for the @mod_forum tag (mdk behat --tags @mod_forum)