* fix validation in new form layout
* pin mediatr to last oss version
* update dependencies
* cleanup code in core
* cleanup code in ffmpeg
* cleanup code in infra
* cleanup code in scanner
* cleanup code in application
* cleanup main code
* cleanup test code
* solution-wide code cleanup
* add deco groups and decos; set default deco for block playout
* use block playout default deco for watermark
* add deco templates, groups and deco template editor
* associate deco template with playout template
* use deco template item watermark for playback
* update changelog for decos