preload post policies on assignments page
preload post policies on assignments page

Test Plan
- Specs pass.

Change-Id: I7535b51ce46d80c9fec954231dd09b80e377e869
Reviewed-on: https://gerrit.instructure.com/211815
Reviewed-by: Keith Garner <a1a80143a840c140f31c3495ebbd9ec906e09fed@instructure.com>
Reviewed-by: Adrian Packel <9c6a39807293376f29cba17542b4cb1b663ecc4a@instructure.com>
Tested-by: Jenkins
QA-Review: Gary Mei <4dff5ebcff9ed76793b70b9470ac64791a16ed11@instructure.com>
Product-Review: Keith Garner <a1a80143a840c140f31c3495ebbd9ec906e09fed@instructure.com>

instructure/canvas-lms,instructure/canvas-lms,djbender/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,djbender/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,djbender/canvas-lms