registerCallback method
Registers a callback for a specific method.
This method allows you to register a callback function that will be invoked when a specific method is called on the method channel.
Parameters:
method: The name of the method for which the callback is being registered.callback: The callback function to be invoked when the method is called.
Implementation
void registerCallback(String method, Function(dynamic) callback) {
_callbacks[method] = callback;
}