Add back end for Studio video upload feature

This feature allows upload of video assets to S3. This requires that the
VIDEO_UPLOAD_PIPELINE setting be properly configured and that each
course be configured with a token issued by the media team for their
processing purposes (e.g. linking the video with a YouTube channel).

Co-authored-by: Greg Price <gprice@edx.org>
Add front end for Studio video upload feature

Co-authored-by: Chris <crodriguez@edx.org>
Co-authored-by: Mark Hoeber <hoeber@edx.org>
Studio video upload feature template and styling

Co-authored-by: Greg Price <gprice@edx.org>
Merge pull request #6257 from edx/mobile/video-pipeline-squashed

Add video upload feature to Studio