[vulkan] Add option for buffer representations in vTensor (#87622)
This diff adds the option to use a Buffer to store data for a `vTensor` by passing `StorageType::BUFFER` to the constructor of `vTensor`. To enable this change, the construction of `vTensor` and `vTensorStorage` had to be slightly refactored to properly support strides. To summarize the changes:
* `vTensorStorage` now contains no Tensor metadata (such as tensor sizes, strides, and `TensorOptions`) - it now only contains the image extents (if texture storage is used) and the buffer length. Tensor metadata is now managed by `vTensor`. The reason for this is to allow multiple `vTensor` objects to point to the same `vTensorStorage` but with different metadata which may be a useful feature now that Buffer storage is enabled.
* `vTensor` will now compute the strides upon construction based on the requested sizes and memory layout if Buffer storage is requested. Previously, strides were faked by setting them all to 0 as strides do not apply to image textures (this behavior is preserved for texture storage).
Differential Revision: [D40604163](https://our.internmc.facebook.com/intern/diff/D40604163/)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/87622
Approved by: https://github.com/digantdesai
