Updates New Files cog menu for keyboard navigation

fixes CNVS-16811

Test Plan:
	- Enable Better Files Browsing
	- Use the keyboard to go to where the cog menu should be
	- The cog menu should appear when it has focus

Change-Id: I853d70c88958134093b6152def284748d11dbfa0
Reviewed-on: https://gerrit.instructure.com/44224
Reviewed-by: Ryan Shaw <ryan@instructure.com>
Product-Review: Ryan Shaw <ryan@instructure.com>
QA-Review: Jahnavi Yetukuri <jyetukuri@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>