cvmts: replace jpeg-turbo native module with new rust module

This module also does threadpooling internally, so we don't need Piscina anymore (which I'm pretty sure was actually bottlenecking.)

jpegturbo-rs/index.d.ts

@@ -0,0 +1,15 @@
+
+interface JpegInputArgs {
+	width: number,
+	height: number,
+	stride: number, // The width of your input framebuffer OR your image width (if encoding a full image)
+	buffer: Buffer
+
+	// TODO: Allow different formats, or export a boxed ffi object which can store a format
+	// (i.e: new JpegEncoder(FORMAT_xxx)).
+}
+
+/// Performs JPEG encoding.
+export function jpegEncode(input: JpegInputArgs) : Promise<Buffer>;
+
+// TODO: Version that can downscale?