fix(json-logic): ensure custom operators are always available

[eshiota]

This simplifies the lifecycle of JSON Logic custom operators, ensuring they are always registered at the beginning of each createHeadlessForm call and de-registered at its end (in addition to always doing it on every handleValidation call.

The previous logic did it every time applyComputedAttrsToSchema was called. However, we have other places where operators were needed but not available (such as when processing conditions that depend on JSON Logic).

Registering and de-registering operators on every createHeadlessForm and handleValidation call is necessary because JSON Logic maintains a single registry of operators shared across all headless forms. Handling this lifecyle in runtime guarantees each headless form instance has its own set of operators without side effects.