[TIMOB-16782] Window refactor and extras

Refactored:
- Ti.UI.Window
- Ti.UI.AlertDialog
- Ti.UI.TabGroup
- Ti.UI.Tab

Fixed:
- Events on Window, TabGroup, and Tab - `open`, `close`, `focus`, and `blur`
- AlertDialog was not getting garbage collected
- Garbage Collection - App would crash randomly when GC kicked in.

Jira tickets [TIMOB-16782](https://jira.appcelerator.org/browse/TIMOB-16782)