Expand sticker picker to support video, audio, etc

This is a suggestion from someone in the community (I've created this on their behalf).

The sticker picker could also be used for posting audio into the room, similar to how online sound boards work. The audio probably shouldn't play automatically and follow the same embed rules currently in place.

Other types of content that could be posted:
* Videos
* Quotes (for a quote wall between you and your friends, or maybe you have a lot of inspiration)