Expose Typescript types in libSquoosh (#1142)

* Expose type declarations in libSquoosh npm package

* Add comment on why we remove the tsbuildinfo

* Fix PreprocessOptions type

Resize should require at least one of the width, height.
The other options are optional for all preprocessors

* Update libSquoosh README to reflect encode changes

I also removed requiring `await image.decoded` call before calling
preprocess or encode since they decode the image before the operation

libsquoosh/src/index.ts

@@ -22,9 +22,10 @@ type EncoderKey = keyof typeof encoders;
 type PreprocessorKey = keyof typeof preprocessors;
 
 type PreprocessOptions = {
-  resize?: ResizeOptions;
-  quant?: QuantOptions;
-  rotate?: RotateOptions;
+  resize?: Partial<Omit<ResizeOptions, 'width' | 'height'>> &
+    (Pick<ResizeOptions, 'width'> | Pick<ResizeOptions, 'height'>);
+  quant?: Partial<QuantOptions>;
+  rotate?: Partial<RotateOptions>;
 };
 type EncodeResult = {
   optionsUsed: object;