Change Details

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

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