"bsconfig.json" hardcoded in error messages

[cknitt]

Even if the user has a rescript.json, error messages are still talking about bsconfig.json:

https://github.com/rescript-lang/rescript-compiler/blob/4c28fa1ce386f694d7ca83f351d4ff1bb6fe6f30/compiler/bsb/bsb_exception.ml#L63

[fhammerschmidt]

Should be a clickable link, especially if you are in a monorepo with multiple rescript.json files.
So rather show the full path as well.