onnxruntime

1ed8fd90 - [EP ABI] Add APIs to create control flow kernels for plugin EPs (#26927)

[EP ABI] Add APIs to create control flow kernels for plugin EPs (#26927) ### Description Adds APIs to enable plugin EPs to create and register kernels for control flow operators (If, Loop, and Scan). The implementation provides ORT-managed kernel implementations that handle subgraph execution while allowing EPs to provide device-specific helper functions for operations like tensor concatenation and transposition. Key changes: - Adds four EP API functions: `CreateIfKernel`, `CreateLoopKernel`, `CreateScanKernel`, and `ReleaseKernelImpl` for creating control flow kernel implementations - Introduces public helper structures (`OrtLoopKernelHelper`, `OrtScanKernelHelper`) that EPs implement to provide device-specific operations - Updates the example kernel-based EP with kernel registrations for all control flow operators and adds corresponding test models. ### Motivation and Context <!-- - Why is this change required? What problem does it solve? - If it fixes an open issue, please link to the issue here. -->