Compute public URI based on path

I've observed that incorrect URI generation can be a foot gun (why isn't my script loading / I used the wrong function to compute the URI or typo'd a file path), while the structure of a WordPress project is very consistent. We have [code in the asset-loader repository](https://github.com/humanmade/asset-loader/blob/main/inc/paths.php) which can be used to automatically compute a URI based on a file system path. Could we consider bringing that code into here so that we don't need to specify the URI, only the path?