Use JMESPath scalar equality for array containment

[fhgffy]

contains([true], 1) currently returns true, although the scalar expression true == 1 returns false. The same problem occurs for false and zero because array membership uses Python equality.

Use the existing JMESPath comparator for array elements so membership agrees with scalar comparisons. String containment keeps its existing behavior. The comparator is imported at call time because the visitor already imports the functions module.

Tests cover both argument directions, float equivalents, matching booleans, numeric equality, null, strings, empty arrays, and a later matching element. All six boolean/number regressions fail on the original code. On Windows with Python 3.12.2, python -m pytest tests -q passes with 993 passed, 1 skipped, and 12 passing subtests; wheel and sdist builds also pass.

This leaves the separate nested-container equality issue in #372 and string argument handling in #360 to those changes.