K-6 Canvas Theme feature flag
K-6 Canvas Theme feature flag

closes UXS-93

flag=canvas_k6_theme

Change-Id: I4492c7a07f5d1a533f81fb67929d44a4a827f04f
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/232713
Reviewed-by: Gabriel Brady <44920beed94fbec4df9a3f19d184ec56b8445826@instructure.com>
Reviewed-by: Ed Schiebel <0ca8a83847a5889cf05cb219c0ab09f6b646243b@instructure.com>
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
QA-Review: Ed Schiebel <0ca8a83847a5889cf05cb219c0ab09f6b646243b@instructure.com>
Product-Review: Jody Sailor

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