[Assignments] Expand/Collapse All for Assignments

[SandaZG]

Problem statement:

Expand/Collapse All for Assignments is not available. Each group needs to be collapsed or expanded separately. The modules page already has this functionality.

Proposed solution:

Expand/Collapse All could be implemented for Assignments page such that it speeds up management of the page and introduces consistency with the Modules page.

User role(s):

instructor