[Profile Settings] Create User Setting to Expand Discussion Threads by Default

Problem statement:

Currently Discussion replies are collapsed on default. Upon landing on a discussion you can click the Expand Threads button to see all posts. There is no setting to leave this expanded by default, so you don't have to use this button for every discussion.

Proposed solution:

Under User Settings, The Expand Threads feature should have a user level Feature Options setting, so Canvas users can Expand Threads by default.

User role(s):

admin,instructor,student,ta