Explore grouping options to make Timing Control Node behave more like a group

[terracoda]

This complex modular set of controls has many options already. I am wondering if a grouping option would be beneficial for users.

The PDOM subheadings for the Timing Control Node provide meaningful sub-groupings and built-in screen-reader navigation options, but when using Alternative Input alone, the Timing Control Node presents as a series of separate interactive controls rather than a group of related controls.

When a sim has many other controls, e.g., Project Data Lab (phetsims/projectile-data-lab#107 (comment)) the number of Tab Stops in the sim's Play Area and Control Area quickly grows without grouping options.

Is it useful to explore a grouping option for a modular control like Timing Control Node?

Imaging 1 Tab Stop, then group navigation with arrow keys and then regular operation of buttons and radiobuttons once they have focus. Not sure if there are parts of Timing Control Node that I have not seen yet that might make Arrow Key group-item navigation problematic.