Build with forked API instead of depending on PyTorch (#2813)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/2813

## Context

https://github.com/pytorch/executorch/pull/2797 forked the required components from PyTorch-Vulkan into the ExecuTorch directory, which means that building the ExecuTorch Vulkan delegate no longer needs to depend on PyTorch.

This is a simple change to the Vulkan delegate CMakeLists.txt to build using the forked Vulkan API instead of the Vulkan API contained in `pytorch` submodule.

imported-using-ghimport

Test Plan: Imported from OSS

Reviewed By: jorgep31415

Differential Revision: D55660791

Pulled By: SS-JIA

fbshipit-source-id: 3c4b018de1092028d02a7d269d62749a38f98a83