Convert media files to .webp format

[LeagueSandboxBot]

Webp is a more efficient format than jpgs, pngs or gifs, so it's preferred over those. Downside is that most image handling software don't yet support webp format natively

---

Beep, boop, I'm a bot! This issue was created by @Mythic in #development.

[Neekhaulas]

We use mostly images that come from their CDN, I took 5 images from the client but Electron should support webp format