Chore: add deadzone for handling for over-active x/y analog inputs

[ianclawson]

Like the comment in the actual code says:

// Handle edge case where some physcial controllers' (like Xbox) analog sticks report both x/y inputs incredibly granularly,
// resulting in an inability to use the analog stick for only a single directional input at a time, such as in place of a d-pad.
// TODO: ideally this would be a user-configurable threshold, but DeltaCore doesn't currently support configurable settings.

This is similar to #17 , although this implementation is 'deeper' in the controller call stack. For the controllers I tested with, the implementation in #17 didn't work for every screen that handles game controller input -- such as the controller mapping screen -- whereas this implementation works system-wide.

This PR might also not solve every use case that #17 solves. Testing would be appreciated.

[ianclawson]

Closing this to clean up my work list of Open PRs