additional partner data for kaltura

fixes PS-931

test plan
*upload file on files page
*additional partner_data should be available on kaltura
*should include root_acount_id, context_code

Change-Id: If0849dc373acdbbc56cae30434c48adfb016d8c7
Reviewed-on: https://gerrit.instructure.com/28662
Product-Review: Adam Phillipps <adam@instructure.com>
QA-Review: Adam Phillipps <adam@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Brandon Broschinsky <brandonbr@instructure.com>
Reviewed-by: Bracken Mosbacker <bracken@instructure.com>