[vulkan] Refactor vTensor to only maintain texture representation (#80719)
Part of a refactor of the Vulkan codebase.
Differential Revision: [D36940229](https://our.internmc.facebook.com/intern/diff/D36940229/)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/80719
Approved by: https://github.com/kimishpatel
