Creates a resource object with the given uri as location.
The uri is a string containing a valid URI.
If the string is not a valid URI, using any of the functions on
the resource object will fail.
The URI may be relative, in which case it will be resolved against Uri.base before being used.
The URI may use the package scheme, which is always supported.
Other schemes may also be supported where possible.
Source
external const factory Resource(String uri);