[Feat request] customlize the image inline function

[kuoruan]

I want to inline svg files with mini-svg-data-uri

Like what the @rollup/plugin-image do:

https://github.com/rollup/plugins/blob/05fc8b67163aeb9d7875300ce34aaff40c993465/packages/image/src/index.js#L54-L57

It will be better to support customlize the image inline function.