Refactor spine runtime

[johanzhu]

The Galacean Spine runtime code has become quite outdated and is facing issues both in its project architecture and performance. The demand for Spine is gradually increasing, necessitating an urgent refactoring and optimization of the runtime code.

Refactoring includes several aspects:

Project Engineering Optimization #66 #56

• Spine has released higher versions like 4.0, 4.1, etc. The past project structure, unable to fulfill the needs of managing multiple versions, necessitates an update to the project engineering structure.
• Parts of the runtime are coupled with the Galacean editor, which need to be separated in the directory structure.

Loader Optimization

• Support for loading multiple textures. Spine support multi-texture #85 Feat: Multiple texture support #53
• Create material and set texture during loading. Enhancement: Set attachment texture before build mesh #48
• Custom file loading. Enhancing Loader to Manage Temporary Link Scenarios #88

Renderer Optimization

• Optimize code structure for improved code readability.
• Optimize mesh generation logic to improve performance. Enhancement: Isolate sub mesh generate logic #52
• Support for Spine 4.0, 4.1.
• Support for premultiplied mode.
• Use double buffering to improve performance (Performance testing is required to determine if it can enhance performance).
• Calculate bounding box at first rendering frame. Galacean Spine disappear when at the edge of scene (Due to Bounds cut off) #84

[johanzhu]

done