Opening a new M3 app should start with a Form added

[bcm628]

Right now, you need to choose what type of Form you want to add when you create a new M3 app. The app should open with a NavRailLayout Form already added.

Should this Form be used as a Layout for another From already?

[bcm628]

If we change layouts so that the nav rail is actually a component you add to the screen, then there should probably be two options when you open a new M3 app: blank or a multi-page template. The multi-page template should have a Layout Form and a few Forms using that layout with the navigation built-in.