restrict uri in devfile or URL passed in to library to be a file path

[yangcao77]

we currently checks if the uri in devfile / URL passed into parser ends with .yaml extension; if not, we make an assumption that the uri is a repo directory contains devfile.yaml or .devfile.yaml, and append the file name at the end before sending a GET request.

However, it does not work for uri: https://registry.devfile.io/devfiles/nodejs, this uri is a valid devfile URL, and should not append any file name at the end.

To resolve this issue, and avoid any confusion. library should restrict uri in devfile or URL passed in to library to be a file path.