fix(ios): bind the view model instance when creating the state machine

[mfazekas]

On the iOS new runtime the state machine was created before dataBind was resolved, so a script that caches context:viewModel() in init kept the file's default instance instead of the one passed as dataBind. The state machine is now created after binding resolution, with the instance passed via createStateMachine(name, binding:). This covers both instance and by-name binding. Android is unaffected.

script-databinding.harness.tsx covers it with the reporter's fixture: on main the script reports isReady 0 / observedSeed 0, with the fix 1 / 42. The Issue414ScriptBinding reproducer page shows the same as a red/green square.

Not covered: DataBindMode.Auto still creates the state machine without an instance, and swapping dataBind on a mounted view still rebinds the existing state machine. The latter belongs with #403.

Closes #414