motioncontroller: Clean up class and remove unused vars

[FintasticMan]

This PR cleans up the MotionController class and some of the code surrounding it. None of the functionality is changed at all.

It also updates the names of some of the variables to match our style guide.

[github-actions[bot]]

Build size and comparison to main:	Section	Size	Difference
text	406620B	-80B
data	940B	0B
bss	53568B	0B

[Riksu9000]

There are quite a few changes here. The ShakeWake changes and RaiseWake variable name change I'm not sure about.

[FintasticMan]

It's quite difficult to split these changes into separate commits because of how intertwined they are.

I think that lastYForRaiseWake is actually a better name for the variable, so I'll rename it to that. I would have liked to have just used the lastY variable, but that's not easy to do without changing any behaviour.

The ShakeWake changes make the code easier to read IMO. The only potential behaviour change is that if the watch is put to sleep at the same time the shake wake option is turned on, the time delta is lower than it would have been before this change. This means that it's possible for it to wake up immediately after going to sleep if the user is shaking the watch. Before it would only wake up a hundred milliseconds or so later. Seeing as this is a practically impossible situation (and isn't really an issue either way), and I can't see any other changes that impact behaviour, I think that this can be considered functionally the same

[Riksu9000]

I don't see how they're that intertwined. It's difficult to isolate what's been moved where with unrelated changes, while also reasoning about them.

[FintasticMan]

@Riksu9000 I've just split my changes into separate commits, so now it should be easier to understand what's going on.