add file_menu external tools to new files cog menu

test plan:
* add an external tool (see the example xml file
referenced in the ticket) configured for the file_menu
* with new files enabled, the external tool should add
an item in the cog menu for files
* if the file's content-type is unrecognized by the tool
 (i.e. not a standard document/image/video file), the
 item should be disabled

* the external tool should also add an item to the
cog menu for file module items on the modules page

closes #CNVS-17005

Change-Id: I8a5497be2f784d5fc64969baf30e33ae53b5dc1a
Reviewed-on: https://gerrit.instructure.com/45203
Reviewed-by: Jeremy Stanley <jeremy@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Jahnavi Yetukuri <jyetukuri@instructure.com>
Product-Review: James Williams  <jamesw@instructure.com>