Replaced style-inject with style-implant

[ivoilic]

Summary

Replaces style-inject with style-implant which is being actively developed, has additional options, and doesn't include any breaking changes!

Background

I'm submitting this PR because of my own experience attempting to bugfix a project that was using rollup-plugin-postcss. I found my styles where being injected at the bottom rather than top of the head causing them override other styles. I realized this could be "fixed" by passing in an options object for the dependency style-inject. However, with literally only one option, open PRs for missing features, and no updates in 4 years style-inject is lacking. I've created a modern version of this library under the name style-implant. I've done my best to make it a drop in replacement for style-inject without any breaking changes besides the folder structure of the package itself.

Improvements

In addition to adding TypeScript support and tests, style-implant adds the ability to add attributes to your injected style tags and preserve the order of style tags injected in the top of the head.