Create discussion create/edit ff
Create discussion create/edit ff

closes VICE-2460
flag=discussion_create

Test Plan:
 - feature flag is available to turn on/off

Change-Id: Ib86bb33ec86dfc776d90903b91bcde46aec03a21
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/291201
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
QA-Review: Caleb Guanzon <54fa1f30d451e4f3c341a8f3c47c9215fd0be9c6@instructure.com>
Reviewed-by: Jeffrey Johnson <7a0f98bfe168bc29d5611ba0275e88567b492abc@instructure.com>
Product-Review: Jeffrey Johnson <7a0f98bfe168bc29d5611ba0275e88567b492abc@instructure.com>

sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms