Arm backend: Fix VKML init and env for MacOS#18286

bdemirb merged 2 commits intopytorch:mainpytorch/executorch:mainfrom

bdemirb:baris_mletorch1953_vkml-vulkan-init-envbdemirb/executorch:baris_mletorch1953_vkml-vulkan-init-envCopy head branch name to clipboard