Change Details

- under the `swh` cli: `swh loader <loader-type> <url>` - Add registering step within the setup.py's entry_points mechanism - all loaders

- under the `swh` cli: `swh loader --type <loader-type> --url <url> <options>` - Add registering step within the setup.py's entry_points mechanism - all loaders

- under the `swh` cli: `swh loader --type <loader-type> --url <url>` <options>` - Add registering step within the setup.py's entry_points mechanism - all loaders