Blur plugin

Add blur functionality to GreenScreen plugin

changed the description

assigned to @agsantos

added SprintIn progress enhancement labels

Blur works but opencv performance is not that good. Want to try ffmpeg boxblur filter.

https://review.jami.net/c/jami-plugins/+/17334

added SprintTo review label and removed SprintIn progress label

mentioned in commit dd6a62af

closed

added SprintDone label and removed SprintTo review label