Exposed speed slider, but it's weird

src/codecs/jxl/encoder-meta.ts

@@ -1,4 +1,5 @@
 export interface EncodeOptions {
+  speed: number;
 }
 
 export interface EncoderState { type: typeof type; options: EncodeOptions; }
@@ -9,4 +10,5 @@ export const mimeType = 'image/jpegxl';
 export const extension = 'jxl';
 // These come from struct WebPConfig in encode.h.
 export const defaultOptions: EncodeOptions = {
+  speed: 1,
 };