supported cross serialization and runtime merge

[cehongwang]

Description

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Fixes # (issue)

Type of change

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• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
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Checklist:

• My code follows the style guidelines of this project (You can use the linters)
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas and hacks
• I have made corresponding changes to the documentation
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[narendasan]

One minor thing then looks good

[narendasan]

Think you can just add a :Optional[torch.classes.tensorrt.Engine|TRTEngine] above

[cehongwang]

It gives me lots of other errors:

py/torch_tensorrt/dynamo/runtime/_TorchTensorRTModule.py:234: error: Item "None" of "Any | None" has no attribute "streamable_device_memory_budget"  [union-attr]
py/torch_tensorrt/dynamo/runtime/_TorchTensorRTModule.py:237: error: Item "None" of "Any | None" has no attribute "automatic_device_memory_budget"  [union-attr]
py/torch_tensorrt/dynamo/runtime/_TorchTensorRTModule.py:240: error: Item "None" of "Any | None" has no attribute "device_memory_budget"  [union-attr]
py/torch_tensorrt/dynamo/runtime/_TorchTensorRTModule.py:245: error: Item "None" of "Any | None" has no attribute "device_memory_budget"  [union-attr]
py/torch_tensorrt/dynamo/runtime/_TorchTensorRTModule.py:246: error: Item "None" of "Any | None" has no attribute "device_memory_budget"  [union-attr]
py/torch_tensorrt/dynamo/runtime/_TorchTensorRTModule.py:248: error: Item "None" of "Any | None" has no attribute "device_memory_budget"  [union-attr]
py/torch_tensorrt/dynamo/runtime/_TorchTensorRTModule.py:254: error: Item "None" of "Any | None" has no attribute "reset_captured_graph"  [union-attr]
py/torch_tensorrt/dynamo/runtime/_TorchTensorRTModule.py:260: error: Item "None" of "Any | None" has no attribute "use_dynamically_allocated_resources"  [union-attr]
py/torch_tensorrt/dynamo/runtime/_TorchTensorRTModule.py:384: error: Unused "type: ignore" comment  [unused-ignore]
py/torch_tensorrt/dynamo/runtime/_TorchTensorRTModule.py:399: error: Item "None" of "Any | None" has no attribute "use_pre_allocated_outputs"  [union-attr]
py/torch_tensorrt/dynamo/runtime/_TorchTensorRTModule.py:409: error: Item "None" of "Any | None" has no attribute "use_output_allocator_outputs"  [union-attr]
py/torch_tensorrt/dynamo/runtime/_TorchTensorRTModule.py:467: error: Item "None" of "Any | None" has no attribute "set_output_tensors_as_unowned"  [union-attr]
py/torch_tensorrt/dynamo/runtime/_TorchTensorRTModule.py:470: error: Item "None" of "Any | None" has no attribute "are_output_tensors_unowned"  [union-attr]