[ExecuTorch][WebGPU] WGSL shader-variant codegen (vec1/vec4, fp16-ready) + rms_norm dedup#20727

meta-codesync[bot] merged 10 commits into

gh/JCNTH/1/basepytorch/executorch:gh/JCNTH/1/basefrom

gh/JCNTH/1/headpytorch/executorch:gh/JCNTH/1/headCopy head branch name to clipboard