Improve thumbnail in video progress bar

[NicoPennec]

Problem

• On Edit page, there is no thumbnail on video progress bar.
• Too much styling calculation on mouseover progress bar.
• The tile image is not preloading of first init of component.

Solution

• Fix missing tile on video progress for Edit page.
• Refactor frame tile style in order to reduce compute.
• Improve tile preloading on init component.

[frankrousseau]

I'm a little bit concerned by this change. The natural dimensions led too many edge cases. That's why I decided to set the size on the backend size.

[NicoPennec]

@frankrousseau

I'm a little bit concerned by this change. The natural dimensions led too many edge cases. That's why I decided to set the size on the backend size.

After several tests, the dimension given by the video player still seems good to me. But I understand that you prefer to keep this logic on the back-end side.

The dimension given by the Kitsu API (Zou) can be wrong on some cases. So It will be necessary to modify the endpoint[1] to return the correct resolution based on the Display aspect ratio (DAR) for each preview video. (ping @EvanBldy)

[1] GET /api/data/playlists/entities/{id}/preview-files

[frankrousseau]

It's better to ensure a proper computation on the backend side. The solution you propose requires to load the video before displaying the thumbnail.

[NicoPennec]

I removed the commit that was causing debate.