[Vulkan] Remove GLSL Code Gen (#91912)
@bypass-github-export-checks
GLSL Code Gen is not used, so this diff removes
- GLSL parts of ShaderSource
- Anything enclosed by USE_VULKAN_SHADERC_RUNTIME, as well as the flag itself
- gen_vulkan_glsl script
Plus some additional refactoring
Differential Revision: [D41358861](https://our.internmc.facebook.com/intern/diff/D41358861/)
**NOTE FOR REVIEWERS**: This PR has internal Meta-specific changes or comments, please review them on [Phabricator](https://our.internmc.facebook.com/intern/diff/D41358861/)!
Pull Request resolved: https://github.com/pytorch/pytorch/pull/91912
Approved by: https://github.com/mcr229
