[jasperblues]

Port of liberation-data/drivine4j#349 (drivine4j PR #361, merged as 3c5c4e5).

The SQL stores gave null for <, <=, > and >= of two lists. Where the statement makes either side a list, the two are now ordered item by item, as Cypher orders them. The first pair that is not equal decides, and a list that starts the other comes first. A pair with a null, of two kinds, or of two maps that differ is not ordered, so the comparison is null.

• Postgres: list_order walks the two lists by place with a recursive query, as nulls_equal does.
• Oracle: cy_list_order is a PL/SQL function over JSON_ELEMENT_T. It is declared through declare() every time it is called, with no declare-once flag of its own, matching Work an aggregate's argument out first where it would bind a value, so temporal arithmetic or text in an aggregate compiles to kilobytes #244: declare() keeps one copy, and Work an aggregate's argument out first where it would bind a value, so temporal arithmetic or text in an aggregate compiles to kilobytes #244's trial compile gives back what it declared.
  • A statement that writes, and a reduce() step, call no function the query declares. On Oracle, list order is refused there, with the messages the spec expects.
• _compared_items: handles temporal items:
  • zoned values compare as their moments;
  • durations, and values of two kinds, are wrapped as maps of their kind, so they are equal or not ordered;
  • a temporal list beside a text list gives null.
• toString(): refused for a list or a map that the statement makes, as Neo4j refuses it under Cypher 5.
• Spec: synced to v0.6.19.
• Docs: the two bullets drivine4j added, in docs/04-statements.md under "Cypher on Postgres and Oracle": one in the general list, and one sentence in the Oracle bullet beside reduce.

SQL: every v0.6.18 spec statement, 998 of them, compiles byte for byte as before on both Postgres and Oracle. The 33 statements new in v0.6.19 compile to the same SQL as Drivine for TypeScript's, once each library's driver wrapper is normalised.

Tests beyond the spec, ported from drivine4j:

• tests/integration/test_cypher_compiled.py, and its sync copy, cover:
  • [[]] < [[], 1];
  • integers past 2^53;
  • nested and null-bearing temporal lists;
  • [] < [duration('P1D')];
  • list compare in an aggregate's argument;
  • list compare beside a walk;
  • a comparison against a 150-item literal;
  • lists read out of an unwound map.
• tests/unit/test_cypher_compiled_size.py checks that Oracle declares the function once and calls it.
• tests/unit/test_cypher_refusals.py checks the toString() refusal and the two Oracle refusals.

Known limits, kept as they are:

• two parameters whose kind is left open give null (drivine4j#385);
• maps inside lists (drivine4j#386);
• Oracle floats outside NUMBER (drivine4j#383).

Fixes #215