add: LQIP, optional fallback, sizes prop

[lxsmnsyc]

Summary

Adds an inline placeholder for local images, a sizes prop, and a cache for
processed images. The fallback prop becomes optional.

Changes

• Local images ship an inline preview. The plugin emits a 20px WebP copy as a
  data URL plus the dominant color of the image, and the component paints it on
  the aspect ratio box until the image loads. The preview is dropped once the
  image is revealed, so a transparent image does not show it through.
• The preview is on by default at 20px. Pass placeholder: false to skip it, or
  placeholder: { size } to change its width.
• Remote images can return the same { url, color } shape from transformURL.
• SolidImage takes a sizes prop, forwarded to every <source>. Without it
  the browser assumes the image spans the full viewport width and downloads a
  larger variant than it needs.
• The fallback prop is optional. Leave it out and the image is revealed as
  soon as it loads.
• The image now fades in over the preview across 200ms.
• Processed images are cached. The file name covers the source path, the size
  and modification time of the source file, the format, the width and the
  quality. A file that already exists is reused instead of encoded again.
• Changing the quality or editing the source produces a new file name, so a
  stale file is never served. Before this the name came from the source path
  alone.

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/@solidjs/image@3

commit: 2d0d7b9