Add Jelly RDF format support

[lapkinvladimir]

This PR adds read/write support for the Jelly binary RDF serialization format in KGX

Jelly is a compact RDF format integrated with RDFLib via the pyjelly library and provides faster load/save performance for large graphs compared to N-Triples.

What was done

• Added "jelly" to SOURCE_MAP and SINK_MAP
• Implemented streaming Jelly parsing in rdf_source.py using pyjelly’s flat streaming API
• Implemented a true streaming Jelly writer in rdf_sink.py using TripleStream.for_rdflib, avoiding graph construction and buffering
• Added pyjelly = "0.6.2" (compatible with Python 3.9)

Added integration tests covering:

• TSV to Jelly to TSV roundtrip
• Jelly read/write
• Jelly with node filters
• Jelly to TSV export

Notes

Jelly support uses pyjelly 0.6.2, because KGX currently targets Python 3.9.
Once KGX upgrades to Python ≥ 3.10, this can be bumped to pyjelly ≥ 0.7.x

[caufieldjh]

Thanks @lapkinvladimir ! I haven't used Jelly in practice but this looks like a valuable addition.
I'm going to make some minor changes to the dependencies and tests before merging.