Implement intent-sensitive ladder snapping, sprinting

[FailSpy]

More controller improvements!
Addresses #84

• Implemented sprinting on ladders, with exported vars to enable/disable and set sprinting speed on ladder
• is_sprinting will now change correctly so stamina doesn't burn whilst on the ladder for no reason
• Added intent-sensitive ladder movement. Ladder movement will generally prefer "W" being up, but if the player is pointing heavily downwards, then their "W" direction is switched to downwards, and "S" is upwards.
• If the player is looking downwards, and facing opposite the ladder as they enter its collider, it assumes the player is attempting to go down the ladder and snaps them on to it
• Additionally, players should now be able to run perpendicular to a ladder without getting caught on it, as the player now needs to be at least somewhat facing the ladder to go up it.

[Phazorknight]

This is amazing!
Subjectively I feel like jumping while on the ladder has become a bit more "sticky", but I honestly don't mind. the benefits of these changes make navigating ladders way better.

Thank you!