add zero elevator and zero arm commands

[moreheadm]

NO BINDINGS YET (help lol)

[moreheadm]

Looks pretty good.

• The kraken has a stall current of 366 A when run at 12V. So at 0.1 V it will draw around 366 / 12 * 0.1 = 3 A (in reality a bit more because of free current). So it won't spike to 40A. I think though it might a good to test it with a button a few times from a few different starting positions and graph the current.

• It will be good if we SmartDashboard print that in periodic.

Ideally we'd run this automatically on enable if we haven't done it since we booted up. A member variable each subsystem should

[moreheadm]

Also the thing that's sets the position shouldn't run if the command was interrupted, since that means it timed out/got overriden by another command.

[moreheadm]

Are we trying to do this by SVR?

[moreheadm]

Thinking about this more, we can just have this bound to a button. If the lifter ever gets unzeroed, we have the driveteam hit the button.

Given that this happened in practice, we should have this ready for EBR, even chain tension improvements should help.

[moreheadm]

Thoughts on this PR @amzoeee? Let's either close or make progress toward merging.

[amzoeee]

We haven't had issues in competition... but it's a good feature to have I think. I'd prefer to keep this open because it's basically in the testing state now...

@riley-jen , thoughts?