add a new function for create multi-sub mesh

[wingcd]

Re: #

Changelog

• add createDynamicMeshes function in MeshUtils for support create multi-sub mesh

---

Continuous Integration

This pull request:

• needs automatic test cases check.

  Manual trigger with @cocos-robot run test cases afterward.

• does not change any runtime related code or build configuration

  If any reviewer thinks the CI checks are needed, please uncheck this option, then close and reopen the issue.

---

Compatibility Check

This pull request:

• changes public API, and have ensured backward compatibility with deprecated features.
• affects platform compatibility, e.g. system version, browser version, platform sdk version, platform toolchain, language version, hardware compatibility etc.
• affects file structure of the build package or build configuration which requires user project upgrade.
• introduces breaking changes, please list all changes, affected features and the scope of violation.

[github-actions]

Code Size Check Report

Wechat (WASM)	Before	After	Diff
2D Empty (legacy pipeline)	1009524 bytes	1009524 bytes	✅ 0 bytes
2D All (legacy pipeline)	2674869 bytes	2674869 bytes	✅ 0 bytes
2D All (new pipeline)	2765738 bytes	2765738 bytes	✅ 0 bytes
(2D + 3D) All	10022093 bytes	10023604 bytes	⚠️ +1511 bytes

Web (WASM + ASMJS)	Before	After	Diff
(2D + 3D) All	16841152 bytes	16842666 bytes	⚠️ +1514 bytes

Interface Check Report

! WARNING this pull request has changed these public interfaces:

@@ -4121,8 +4121,16 @@
              * @param options @en options of creating @zh 创建选项
              * @return @en The created dynamic mesh, which is same as out @zh 新创建的动态网格，同 out 参数
              */
             static createDynamicMesh(primitiveIndex: number, geometry: primitives.IDynamicGeometry, out?: Mesh, options?: primitives.ICreateDynamicMeshOptions): Mesh;
+            /**
+             * @en create a dynamic mesh, which supports multiple sub meshes.
+             * @zh 创建一个动态网格，支持多个子网格。
+             * @param geometries @en geometry data use for creating @zh 用于创建的几何数据
+             * @param out @en output dynamic mesh @zh 输出的动态网格
+             * @return @en The created dynamic mesh, which is same as out @zh 新创建的动态网格，同 out 参数
+             */
+            static createDynamicMeshes(geometries: primitives.IDynamicGeometry[], out?: Mesh): Mesh;
         }
         export function readBuffer(target: DataView, format?: gfx.Format, offset?: number, length?: number, stride?: number, out?: number[]): number[];
         export function writeBuffer(target: DataView, data: number[], format?: gfx.Format, offset?: number, stride?: number): void;
         export function mapBuffer(target: DataView, callback: (cur: number, idx: number, view: DataView) => number, format?: gfx.Format, offset?: number, length?: number, stride?: number, out?: DataView): DataView;