* Add Scheduled Lives functionality through originallyPublishedAt
Implements #6604 by reusing the originallyPublishedAt field of isLive videos to mark "waiting for live" videos as scheduled at a set time.
* Hide scheduled lives from Browse Videos page
* Add tests for Scheduled Live videos
* Make scheduled lives use a dedicated scheduledAt field in the VideoLive table
* Plan live schedules to evolve in the future
* Use a dedicated table to store live schedules, so we can add multiple
schedules in the future and also add a title, description etc. for a
specific schedule
* Adapt REST API to use an array to store/get live schedules
* Add REST API param so it's the client choice to include or not
scheduled lives
* Export schedules info in user import/export
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Co-authored-by: Chocobozzz <me@florianbigard.com>
* Add NSFW flags to videos so the publisher can add more NSFW context
* Add NSFW summary to videos, similar to content warning system so the
publisher has a free text to describe NSFW aspect of its video
* Add additional "warn" NSFW policy: the video thumbnail is not blurred
and we display a tag below the video miniature, the video player
includes the NSFW warning (with context if available) and it also
prevent autoplay
* "blur" NSFW settings inherits "warn" policy and also blur the video
thumbnail
* Add NSFW flag settings to users so they can have more granular
control about what content they want to hide, warn or display
* Use a table to list my videos for a clearer overview and so it's
easier to add bulk actions in the future
* Use a "Manage" video page with a proper URL navigation
* Add "Stats" and "Studio" in this "Manage" page
