Feat/fullscreen support

[m-abs]

PR Checklist

• [ ] The PR title follows our guidelines: https://github.com/Notalib/nativescript-webview-ext/blob/master/CONTRIBUTING.md#commit-messages.
• [ ] There is an issue for the bug/feature this PR is for. To avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it.
• [ ] All existing tests are passing.
  • [ ] On Android
  • [ ] On iOS 9
  • [ ] On iOS 10
  • [ ] On iOS 11
  • [ ] On iOS 12+
• [ ] Tests for the changes are included

What is the current behavior?

What is the new behavior?

Fixes/Implements/Closes #[Issue Number].

[m-abs]

Note this is only supported on android. WKWebView have no official way to support requestFullscreen.