Base on / merge into rehype-inline-svg

[marko-knoebl]

Possible goal: merge with rehype-inline-svg (https://github.com/JS-DevTools/rehype-inline-svg)

rehype-inline-svg is a more sophisticated tool for inlining and optimizing SVGs (see JS-DevTools/rehype-inline-svg#2 )

In the future it may be a good idea to incorporate both tools into a single tool.