fixes CNVS-6696
test plan:
1) use postman to make a request to this new endpoint for a group category that
has unassigned members
--asynchronous example:
POST http://localhost:3000/api/v1/group_categories/<group_category_id>/assign_unassigned_members
--synchronous example:
POST http://localhost:3000/api/v1/group_categories/<group_category_id> \
/assign_unassigned_members?sync=true
2) verify that the group category's unassigned members have now been assigned
among the available groups
--NOTE: this may take a minute depending on the number of unassigned members
3) verify the api documentation for Group Categories - "Assign unassigned members" makes sense
4) verify that an asychronous request returns a Progress JSON
(see api documentation for example)
5) verify that a synchronous request returns an array of Group Memberships
(see documentation for example)
NOTE: I've made some tweaks to the current Groups page such that you can
still randomly assign students. However, this shouldn't matter because
it's all getting replaced anyway.
Change-Id: I894ff2b1e11c7919a110b5159710683869caedc4
Reviewed-on: https://gerrit.instructure.com/22044
Reviewed-by: Jon Jensen <jon@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Marc LeGendre <marc@instructure.com>
QA-Review: Marc LeGendre <marc@instructure.com>
261d7725dc