Expose Arrow CSR and table registration

[adsharma]

Summary

• expose Arrow-native query results through query_as_arrow and CSR arrays through QueryResult::csr
• add Rust Arrow RecordBatch APIs for registering Arrow node, relationship, and CSR relationship tables
• wire the C++ shim and cxx FFI needed for Arrow table registration and native Arrow chunk iteration

Validation

LBUG_PRECOMPILED_RUN_ID=26256190740 cargo test --release --features arrow --lib