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Conclusion: Export `CreateSyncTokenForCurrentExternalContext`, but the newly created shared_ptr might be difficult to manage lifecycle at C# side, so I directly export a new interface in `GlTextureBuffer` to simplify the usage...

@NoelStephensUnity Understand, so I think it might be better to add some documents or comments for this component to make it more clear.

See https://github.com/BoomingTech/Piccolo/pull/496