[TIMOB-28367] TiAPI: Ti.UI.ProgressBar should smoothly animate value changes

*Summary:* Our [Ti.UI.ProgressBar](https://docs.appcelerator.com/platform/latest/#!/api/Titanium.UI.ProgressBar) should animate by default when changing the progress value. This will make the UI widget look more modern. We should provide a new "animated" property which allows developers to enable/disable the animation. By default it should be true. *To-Do on iOS:* iOS (/iphone/Classes/TiUIProgressBar.m): *animated:YES*

- (void)setValue_:(id)value
{
  CGFloat newValue = ([TiUtils floatValue:value] - min) / (max - min);
  [[self progress] setProgress:newValue animated:YES];
}

*To-Do on Android:* When we switch over to the material [LinearProgressIndicator](https://developer.android.com/reference/com/google/android/material/progressindicator/LinearProgressIndicator), we can easily animate progress value changes via its [setProgressCompat()](https://developer.android.com/reference/com/google/android/material/progressindicator/BaseProgressIndicator#setProgressCompat(int,%20boolean)) method. We can do this once ticket [TIMOB-28351] is implemented. Note that the way to do this with the old Android [ProgressBar](https://developer.android.com/reference/android/widget/ProgressBar) class is to do the below.

ObjectAnimator.ofInt(progressBar, "progress", progressValue)
    .setDuration(300)
    .start();