Expose decompressing

`bin-wrapper` is a bit of a black-box if the use-case doesn't fit exactly how `bin-wrapper` works.

For example I had the need to decompress `.tar.xz` which requires a plugin to `decompress` and this is impossible because of all the leaky abstractions.

I had to [hack](https://github.com/sindresorhus/infer-bin/blob/5a14b7c4154401caea84d538764c5a1ddac53c40/lib/index.js#L18-L38) around in the meantime...

Start by reading the bin-wrapper API and the linked workaround in infer-bin/lib/index.js, then inspect how the decompress dependency is hidden. Compare the requested .tar.xz use case with decompress's plugin requirement. Done means callers can provide the needed decompression behavior without relying on leaky internal abstractions.

Written by the indexing model from the issue text.