Add Lockable Doors and Refactor Door Animations and Collisions

[emrecrpnl]

This pull request introduces lockable doors and improves door animations. The changes are as follows:

1. The door.tscn file has been updated to allow doors to be locked, and the existing open-close animations have been integrated into the game.
2. The door models in structure.tscn and core.tscn have been hidden and replaced with the newly updated door.tscn file.
3. The necessary collision objects have been adjusted to allow players to pass through the doors when unlocked.

Purpose of these changes:
The goal of these updates is to make it easier to expand the game's map. By using lockable doors, additional rooms and areas can be added behind them, enabling the creation of new quests and gameplay dynamics.