Improvements to vdoninja support

[timotheeg]

Some improvement to handling vdo.ninja player cams

• Brings the vdo ninja url into the admin page, so an admin can copy it if needed
• Adds a full-size focused video in the league layout to show the selected player video cam full screen
• Adds a new layout vdocams to only show player cams (not gameplay). This can be useful for restreamer who need to have access to the player cam feed easily