Research Package - Add media step

[bardram]

An RPStep implementation which can display a video or image as a step during surveys

Open questions:

• Where to upload the media? (YouTube? Resources on the portal? Any link?)
  • You can parse the URL with a regex to decide what kind of player to use (YouTube/other)
• What kind of media to support?
• Pictures?
• Audio files?

[bardram]

Resources should be:

• audio
• video
• image

all accessible from an URL or a Flutter asset.

[bardram]

For video - use https://pub.dev/packages/video_player ?