Deadzone shapes

[100-TomatoJuice]

Currently, the only type of deadzone for a DualAxis is a cross shape. This shape is preferred for some instances, like in Rocket League, as the cross-shape deadzone makes directional flipping easier. However, there are instances where a circular or rectangular deadzone is preferred, like a twin-stick shooter.

Adds DeadzoneShape to DualAxis, which allows the user to choose between a circle, rectangle, and a cross for the deadzone shape.

From manual tests, the shapes appear to be correct and all work. This pr also passed cargo test.

Things to do:

• Add tests to make sure the deadzones shapes are correct
• Implement Hash for DeadZoneShape
• Change tests that relied on Cross snapping
• Improve documentation of DeadzoneShape (feels a little convoluted)
• Update RELEASES.md

Questions

1. Is extract_dual_axis_data() the correct method to test the different shapes?
2. Adding include_deadzone: bool to input_value() feels a little gross, but I didn't find a better way to get the input_value of a SingleAxis without it running its deadzone. Is there a better, perhaps overlooked, way of doing this?
3. Currently, the shapes diamensions rely on the x and y thresholds in SingleAxis. This keeps inverting of the input easy, but might create confusion? with_deadzone() has been changed to hopefully make this easy, but there might be a better way.

[alice-i-cecile]

WRT question 3, I'm increasingly convinced that we probably don't even want to store a SingleAxis inside of DualAxis: it's overly clever and the abstraction doesn't quite work. @paul-hansen, @Shatur: do either of you have opinions on that (or the rest of this PR)?

[Shatur]

Never used this API, so I don't have an opinion on it :(