Add Gremlin graph storage

[alllexx88]

Add Gremlin graph storage.

Note that at least my setup suffered from an anyio issue, that has been fixed a couple of days ago, with commit agronholm/anyio@c518300 so I had to install it from git before the next version is released.

[alllexx88]

I see the linting error report, due to logging.basicConfig(format="%(levelname)s:%(message)s", level=logging.WARN) line before the lightrag imports. I can fix it, but setting logging level with this line doesn't change the loglevel when issued after lightrag imports.

[LarFii]

Thank you for your contribution! To avoid the linting error during , you can temporarily comment out this line. Additionally, you can add a comment to describe its functionality.

[alllexx88]

Thanks @LarFii ! Done together with one little fix (using await asyncio.gather instead of consecutive awaits in get_node_edges())

[LarFii]

Thanks!