- Set a new `externalFrame` property when the external container config is provided.
- Use the new instance var is over the existing `frame` var.
	- This was done to isolate the new usage from the existing usage of `frame`
	- The existing usage of `frame` applies control over the sidebar frame, which works against what we want with `externalFrame`
- Make the uses of `frame` conditional.
	- These are the statements that are not invoked when the external container is specified.
	- The one case where we do want to use either frame is when emitting `onLayoutChange`
- Refactor the Sidebar tests to test for the added implementation and usage