Livestreaming

[ferishili]

This PR fixes #814,

Description:

please refer to issue. Basically, this PR brings Livestream scheduling capability to the plugin.

Concept:

• To activate Livestream feature, admin must select a compatible livestream workflow for each capture agent in the setting. If empty, the feature is considered deactivated (refer to comment for more help on livestream workflow)
• On schedule recording page in a course (dozent view), a new button in the action column will be displayed called "LIVE", with which one could schedule that appointment but as livestream.
• On schedule recording page in a course (dozent view), the playlists for both scheduled recordings as well livestreams could be selected from the action menu in the sidebar.
• When a livestream is scheduled it will be allocated in the selected playlists and will be displayed like normal video but with a few limitations, and a counter will be displayed on default preview image.
• When a livestream is Live, then the video in the playlist will change to LIVE with the duration counter. In this state the video will become clickable which redirects to the livestream video.
• The cronjobs are changed to recognize the livestream event for (before, during and after) the appointment.

NOTE:

As of writing this PR description, the available test environment was not capable of providing right publication and streaming a real live-event. Therefore, it is necessary to test against a real one.

[github-actions[bot]]

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