zhuxudong

Fix sub asset repeated loading

3

## Summary by CodeRabbit - **New Features** - Improved handling and management of sub-asset promises, enhancing the stability and reliability of asset loading. - **Refactor** - Streamlined URL construction logic...

Support post process

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### Please check if the PR fulfills these requirements - [x] The commit message follows our [guidelines](https://github.com/galacean/engine/blob/main/.github/COMMIT_MESSAGE_CONVENTION.md) - [ ] Tests for the changes have been added (for bug fixes...

support extension: https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_materials_emissive_strength

The latest specular specification： https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_materials_specular And the original extension should be deprecated: https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Archived/KHR_materials_pbrSpecularGlossiness

I want move the editor code to the `include "editorProp.glsl"` 

``` .load({ type:AssetType.Project, url:"***" }).onProgress((loaded, total)=>{},(identifier, loaded, total)=>{}) ```

The code in the ShaderLab macro cannot determine whether it is a vertex or a fragment.

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``` #ifdef test void test(){} #endif vert(){ } frag(){ test() } ```

will throw error ``` #define test float a2; ``` temporary solution ``` #define test 1 float a2; ```

Refactor pbr shader api with ShaderLab

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Refactor the pbr shader api of the `engine-toolkit` package to facilitate users to expand materials.