* added previous and next buttons
* previous and next notebook API
* links for prev/next notebooks
* fixed first and last pages
* made code more readable
* addressed Kevin's comments
* moved logic over to BookTreeItem
* show buttons in dev mode only
* added BookTreeItemFormat interface
* added interface and enum
* removed localize call
* Basic touchbar support
* Touchbar support for Run Cell, Run Query, Add Cell
- Add top 3 notebook commands
- Add top query command
Actions only appear on having active editor of expected type.
In order to make Notebook work as expected, added tabindex to support focusing
and hide outline to ensure it doesn't get weird blue outline on click
Note: does not have icons yet, which would be nice.
However can add in subsequent PR once this comes from UX.