Fix acceleration reset on overlapping mouse keys

[esawady]

See #21494. Prior to this fix, moving the mouse diagonally would skip the first MOUSEKEY_MOVE_DELTA frames of acceleration.

Description

I'm not entirely sure this is the behavior we want - resetting acceleration when going from eg. moving up to moving up-right doesn't seem quite right. However, I'm pretty confident that this is what the original patch was meant to do.

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout/userspace (addition or update)
• Documentation

Issues Fixed or Closed by This PR

Checklist

• My code follows the code style of this project: C, Python
• I have read the PR Checklist document and have made the appropriate changes.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[filterpaper]

I'm pretty confident that this is what the original patch was meant to do.

#21494 was designed to reduce (jarring) continual increase in acceleration with a new direction. Reseting both values to restart completely from zero, however, was not the original intent.

resetting acceleration when going from eg. moving up to moving up-right doesn't seem quite right

This (default) behaviour can be polarising due to user preference. Created #23341 as an enhancement to make this feature optional for users.

[github-actions]

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