Allows for using larger(or smaller) than the default `20px` width, trading size for quality via more/less pixels.

Adds the `base64Width` arg to the fixed & fluid nodes.

Provides added clarity for where these numbers are used.

Especially for the value of `72` where it's not clear if the value was for image or display density. `defaultBase64Width` improves clarity and keeps it DRY across both usages.

Place the `backgroundColor` div before/behind the placeholder img.

They seem all intended to use the same duration of `0.25s`, `fluid` backgroundColor div actually used `0.35s` for some reason which seemed a possible typo, this corrects that and avoids it in future.

For example, WEBP base64 placeholders with a `backgroundColor` as fallback while using JPG/PNG with WEBP for the `<picture>` element.

Adds the `forceBase64Format` config option.
Adds support for WEBP base64 images.

Allows setting a project wide default, rather than having to request it per image.

Updates `defaultBase64Width` to be a function as `pluginOptions` has not initialized when assigned.

Co-Authored-By: polarathene <polarathene@users.noreply.github.com>

Co-Authored-By: polarathene <polarathene@users.noreply.github.com>