Class
Common
```kotlin
public class MutableTransitionState(initialState: S) : TransitionState()
```
MutableTransitionState contains two fields: `currentState` and `targetState`. `currentState` is
initialized to the provided initialState, and can only be mutated by a `Transition`.
`targetState` is also initialized to initialState. It can be mutated to alter the course of a
transition animation that is created with the `MutableTransitionState` using
`rememberTransition`. Both `currentState` and `targetState` are backed by a `State` object.