The Dreaded `ConfigCommand.py` Refactor `[AARD-1764]`

[BrandonPacewic]

I am happy to report that this file is now less than 240 lines. 😊

• Set a default size for the main config panel:
  • This was done to solve an issue with the joint and gamepiece config tables not showing up correctly.
• Removed unused handler code.
• Remove unused code within ConfigCommand.py.
• Removed preselect handler as it simply was not working as originally intended.
• Updated the help icon redirect to be directly to the exporter codelab.
• Changed the default location for export to be local download.
• Moved handler creation to the top of create:
  • Results in more stable behaviour if we crash later when adding joints, wheels and gamepieces.
• Added PersistentEventHandler class that will auto add a handler to the global list to keep it from falling out of scope.
• Added better typing with adsk.fusion.Design.cast(adsk.core.Application.get().activeProduct) for the design getter call.
• Fixed a persistent issue from #1099.

JIRA Issue