rdf to-jelly: implement the GRAPHS stream type

[Ostrzyciel]

Issue: #101

[Ostrzyciel]

@adanilenka requesting confirmation that it works for your use case

[adanilenka]

the build: https://github.com/Jelly-RDF/cli/actions/runs/14759611428/artifacts/3039362901

was tested with the following set of sample N-quads input file (coming from pos_005 quads test), featuring a mix of graphs in a variety of forms (but not generalized RDF):

<http://example.org/resource/A> <http://example.org/property/p1> <http://example.org/resource/B> .
_:bn2 <http://example.org/property/p2> "100"^^<http://www.w3.org/2001/XMLSchema#integer> <http://example.org/graph/G>.
<http://example.org/resource/A> <http://example.org/property/p3> _:bn3 _:bn1.
<http://example.org/resource/A> <http://example.org/property/p3> _:bn3 _:bn1.
<http://example.org/resource/A> <http://example.org/property/p3> _:bn3 _:bn1.
<http://example.org/resource/E> <http://example.org/property/p2> "0.01"^^<http://www.w3.org/2001/XMLSchema#float> .
<http://example.org/resource/E> <http://example.org/property/p2> <http://example.org/resource/F> _:bn1 .
<http://example.org/resource/H> <http://example.org/property/p2> "0.1"^^<http://www.w3.org/2001/XMLSchema#float> <http://example.org/graph/G1>.
_:bn2 <http://example.org/property/p1> "200"^^<http://www.w3.org/2001/XMLSchema#integer> <http://example.org/graph/G>.
_:bn2 <http://example.org/property/p1> "200"^^<http://www.w3.org/2001/XMLSchema#integer> <http://example.org/graph/G1>.
_:bn2 <http://example.org/property/p1> "200"^^<http://www.w3.org/2001/XMLSchema#integer> .
<http://example.org/resource/A> <http://example.org/property/p> <http://example.org/resource/B> .
<http://example.org/resource/E> <http://example.org/property/p1> <http://example.org/resource/F> .
<http://example.org/resource/A> <http://example.org/property/p> _:bn3 <http://example.org/graph/G> .

the file was serialized in the following modes:

• single frame with and without prefix table
• multi-frame (15 rows per frame)

and validated compared to the input file with --compare-ordered=true

So far, no critical issues have been detected. The only tiny thing is that the logical type is set to undefined, which is okay from the specification POV but can be "perfected" later.

[Ostrzyciel]

Ah, the logical stream type should be set to something by default, good catch. I'll add it in a sec.

[Karolina-Bogacka]

this logic could be moved to a separate method (to make sure both conditions are always correctly checked in the if)

[Ostrzyciel]

Eh, that's how it is in the Jena original. Let's keep it as-is.