Improves folder renaming with keyboard navigation

fixes CNVS-16810

Test Plan:
	- Enable Better File Browsing
	- Use your keyboard to go to the add folder button
	- Add a folder and press 'Enter' to finish it.
	- Focus should be on the new folder
	- Add a folder again, but this time press 'Escape' to cancel editing
	- Focus should be back on the Add Folder Button
	- Use your keyboard to go to a file and use the gear menu to
	  edit it's name, press enter.
	- The file should have focus
	- Edit a name again, this time pressing escape to cancel
	- The file should have focus

Change-Id: Ic6eb42943ca757c49cd8d9e65bea4f4af006c8d0
Reviewed-on: https://gerrit.instructure.com/44221
Reviewed-by: Dan Minkevitch <dan@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Nathan Rogowski <nathan@instructure.com>
Product-Review: Cosme Salazar <cosme@instructure.com>