Replay operator helpers

The out parameters on GetReplayOperatorByName are C# out params; Jint surfaces them as additional fields on the returned wrapper object.

Function	Returns	Description
`GetReplayOperatorByName(sceneName: string, layerName: string, operatorName: string)`	`AbstractOperator or null`	Looks up a `ReplayOperator` by scene/layer/operator name. On success, also returns the current frame-store window, frame count, and playback state via the out parameters. Returns the operator, or null if any lookup fails. Concrete `ReplayOperator` members are reached from script with `GetObjectProperty` / `CallObjectFunction`.
`StartReplayOperatorByName(sceneName: string, layerName: string, operatorName: string, startDateTime: DateTime, stopDateTime: DateTime)`	`bool`	Starts replay playback on the named operator over the given time window. Returns false if the operator is not a `ReplayOperator`, or if it is already playing back.
`GetReplayOperatorPlaybackStoppedByName(sceneName: string, layerName: string, operatorName: string)`	`bool`	Returns true when the named replay operator is not currently in `Playback`. Returns false if the operator is missing or is not a `ReplayOperator`.