Refactor UserInput into Buttonlike, Axislike and DualAxislike

[alice-i-cecile]

Fixes #535.

This is a major refactor that splits user inputs into three kinds: buttonlike, axislike and dualaxislike.
This change ends up rippling through the whole stack: from Actionlike to UserInput to InputMap to ActionState.

Despite that, I'm really happy with this change! It really clarifies the semantics of the different input types, in a way that I think will be easier to learn, more natural to maintain and harder to mess up.

There are a number of items that need to be done before this is mergeable still:

• rename with_dualaxis to with_dual_axis
• generate ActionDiffs correctly
• sanity-check clashing inputs
• actually update axislike and dualaxislike data in ActionState::update's call stack
• fix the lengths of all of our different user input kinds
• go over ActionState to double-check that all APIs have been updated correctly
• make everything compile
• cargo fmt
• cargo clippy
• get tests passing 🥲

Follow-up

This PR is already way, way too big. In the interest of sanity, some functionality has been omitted / left broken in this PR.

• store 0-1 values in Buttonlike inputs to properly handle triggers
• fix clash handling for dpads
• fix action diffing