[HMI] Mars' Flying N Diving animations

🚀A smooth falling animation has been added - when you look down, and when you press the Shift, it is more aggressive, as it was before.

🌟During normal flight, when you hold an object in your main hand, the offhand disappears from the screen - this is mainly about creative mod

🎯Improved animation to feel more fluid and lively

🚀Animation now stays active while flying

🌟Crouching now slightly moves the hands forward for better visual feedback