Like D12571, but for the {nav View Properties} Window. Also did a little bit of re-organization. This allows us to use a `QFormLayout` as the top-level layout and simplify the code a lot, including no longer using the now-unnecessary paradigm of putting a layout inside a `QWidget`, and ending the use of `QGridLayout` to make a fake and more complicated form-style layout.
Depends on D13749