[ET-VK] Enable Partial GPU lowering via Vulkan in stories model export#2368

SS-JIA wants to merge 4 commits intogh/SS-JIA/13/basepytorch/executorch:gh/SS-JIA/13/basefrom

gh/SS-JIA/13/headpytorch/executorch:gh/SS-JIA/13/headCopy head branch name to clipboard