Parcel 2: Image Resizing Transformer

[devongovett]

Create the @parcel/transformer-image-resize package. This should include a Transformer plugin that resizes images using the sharp library. It should accept options via query parameters to determine what size to resize the image to.

For example, you could reference an image like this to resize it to 200px wide:

<img src="./image.jpg?width=200" width="200">

This would also work anywhere images can be referenced, e.g. CSS or JS.

This transformer should be included in @parcel/config-default in a pipeline for *.{png,jpg,jpeg}. However, in order to improve development build performance, it should only run in production mode. This should be safe as long as users are using explicit sizes on their image tags in addition to their URLs. Also, if no query params are provided to the image url, the plugin should do nothing.