Allow "favorite" videos (heart icon)

[whyboris]

Seems like an easy thing to add and some people might prefer this over the 5-star rating system.

Proposal: A "favorite" video, indicated by a heart icon in the top-left of a thumbnail (not shown on a folder when in folder view), is equivalent to a 5-star rating. This means any 5 star video automatically has the heart on it, and removing the heart from it removes the 5-star rating. No additional metadata field will be added to the video.

Importantly there will be a toggle to hide the hearts -- letting those who don't want to see them to not see the hearts.

Should be an easy add 👍