MultipleFileContentsByRef is joining paths when it shouldn't

[alfredodeza]

This was introduced/modified when writing tests assuming that MultipleFileContentsByRef didn't have a full path already. Specifically this part:

func (s DirectoryResolver) MultipleFileContentsByRef(f ...file.Reference) (map[file.Reference]string, error) {
	refContents := make(map[file.Reference]string)
	for _, fileRef := range f {
		resolvedPath := path.Join(s.Path, string(fileRef.Path))
		_, err := os.Stat(resolvedPath)
		if os.IsNotExist(err) {
			continue
		} else if err != nil {
			log.Errorf("path (%s) is not valid: %v", resolvedPath, err)
		}

There shouldn't be a path.Join at all here. Tests need to be updated as well