refactor: sprout a class for kaltura bulk uploading

gets a big method out into its own class in preparation for further
refactoring.

Change-Id: I307aa4c61c50cf9112fdf8a6e40dff4dd2b381a7
Reviewed-on: https://gerrit.instructure.com/39444
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Zach Pendleton <zachp@instructure.com>
Product-Review: Paul Hinze <paulh@instructure.com>
QA-Review: Paul Hinze <paulh@instructure.com>