[Glitch] Add WebP support

Port 5092d17f29  to glitch-soc

app/javascript/flavours/glitch/util/resize_image.js

@@ -31,7 +31,7 @@ const loadImage = inputFile => new Promise((resolve, reject) => {
 });
 
 const getOrientation = (img, type = 'image/png') => new Promise(resolve => {
-  if (type !== 'image/jpeg') {
+  if (!['image/jpeg', 'image/webp'].includes(type)) {
     resolve(1);
     return;
   }