Add relationship list predicates

[j6k4m8]

Adds relationships() for materializing selected path relationships and implements ALL, ANY, NONE, and SINGLE predicates with scoped loop variables, compound conditions, multigraph support, and Cypher-compatible null semantics.

[codspeed-hq]

Merging this PR will not alter performance

✅ 99 untouched benchmarks

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_{Comparing relationship-list-predicates (372dac6) with master (b9fbf23)}