Add toggle reaction wheels tweakable

[Bobe]

It took me some time to realize that the reason some of my rockets bending and wobbling like an arrow in slow motion (for reference:

) is that there were two sets of reaction wheels fighting one another. This is what I believe anyway.

Typically when launching a payload that has its own guidance system and possibly a separate reaction wheel, the rocket itself has a guidance system and a reaction wheel, usually 1.25m and 2.5m respectively between the payload and the rocket. So when launching, the two SAS systems are trying to fly the rocket and it seems like they end up creating some kind of resonance that ultimately wants to snap the rocket in half.

I'm able to disable the payload's reaction wheels on the launchpad, but it would be so much more convenient if I could do it in the VAB, especially when I'm using KW Rocketry fairings and I have to randomly click until I find the part.