Add success and error callbacks for the overlaysWebView method

[CodeWithOz]

Feature Request

Motivation Behind Feature

I need a way to know when the overlaysWebView method has completed its work, so that I can ensure that my custom javascript logic is always run after the native code has been executed. Right now I can do this:

StatusBar.overlaysWebView(false)
myCustomLogic();

But myCustomLogic may actually get executed before the statusbar stops overlaying the webview.

Feature Description

I think a good solution is to use the callback system that we're already familiar with. The code snippet above could therefore become:

StatusBar.overlaysWebView(false, myCustomSuccessLogic, myCustomErrorLogic);

I don't expect this to break anything for existing users, I believe this change will be an extension of the current functionality and may prove useful for other developers.

Alternatives or Workarounds

I forked the plugin and made the changes needed for Android so that I could test that it works well for me. You can check the 3 most recent commits on my fork. I can create a PR for this too if needed, though my fork doesn't include the required iOS changes.