Add support for BufferView copy and cross-dev-type transfer in python runtime

[devtbi]

TL;DR

Added support for copying HAL buffer views between/on devices.

What changed?

• Added AllocateBufferViewCopy method to HalAllocator to enable copying buffer views between/the same devices
• Added CreateViewLike method to HalBuffer to create views with matching characteristics
• Added ExportBuffer and ImportBuffer methods to support cross-device buffer transfers
• Added GetInfo method to HalDevice to retrieve device identifier and ID
• Updated Python type hints and bindings to expose new functionality
• Added tests to verify buffer view copying behavior, including sliced views

[devtbi]

• Add support for BufferView copy and cross-dev-type transfer in python runtime #28 👈 (View in Graphite)
• Call PyGILState_Ensure in CheckApiStatus error case #48
• integrate-iree-20250217

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[maxbartel]

I think this should be good. However can you explain the import and export functions a bit? Maybe even with a small rationale?

[devtbi]

Yep, the export/import is needed here, because transfering memory expcets the buffers to be of the same buffer-type (every driver has its own buffer type).. so one of the buffers first has to be exported from the original allocator, and imported into the type of the device performing the transfer. So..
iree_hal_allocator_export_buffer, is used to get a raw pointer to the underlying memory of the buffer & with import you can create a handle to that memory in the native buffer type- all assuming that the orignal buffer is kept alive & the user has to ensure that the memory is actually accessible by the target.
Also used for the dlpack import & export mechanism.