Add 'player_physics' table in dimension definition

[1SDANi]

It can have the following fields (all optional):

• gravity: Gravity (constant -z velocity)
• jump_speed: Jump speed.
• jump_antigravity: The gravity is decreased by this amount while holding the jump key prior to the peak of the jump.
• glide_gravity: Fall speed while holding Jump key in this dimension.
• horizontal_sprint_mod: Horizontal sprint speed multiplier.
• vertical_sprint_mod: Vertical sprint speed multiplier.
• move_speed: Movement speed.
• air_speed_mod: The movement speed of players in this dimension is multiplied by this amount while in the air.
• fly_speed: Fly speed in this dimension.
• sneak_verticalSpeed: The vertical movement speed is multiplied by this amount while sneaking.
• sneak_horizontalMod: The horizontal movement speed is multiplied by this amount while sneaking.
• is_sneak_always_mod

OP:

Migrated Move Speed, Fly Speed, Sneak Fall Vertical Speed, and Horizontal and Vertical Sprint Mods declaration to Lua moddabl Dimension attributes

Added Jump Antigravity and Glide Gravity as Lua moddable Dimension attributes:

Holding Jump while moving upwards after a jump will reduce the effects of Gravity on the player, granting them greater control over the height of their Jump. Values of this and Jump height were modifier to preserve the inability to jump 2 full blocks high
Holding Jump while falling will reduce the player's downwards speed cap from being equal to their Move Speed to the Glide Gravity as defined in the current dimension
Move and Process Inputs now require an instance of ClientWorld to be passed to them

[Unarelith]

Overall I really like what you did in your PR and can't wait to merge that. :)

Just check the changes I requested + you should add documentation in docs/lua-api-dimension.md

[Unarelith]

Please edit CONTRIBUTORS.md file and add you to the list