ggml-webgpu: improve i-quants mul_mat performance and speed up prefill (

ggml-org#24530)

* Improve prefill speeds for i-quants

* Fix #if defined() usage in preprocessor guards.

ggml-webgpu: Add clang-format job (ggml-org#24308)

* Add clang-format job

* try local formatting

gguf : fix ftell/fseek for Windows (ggml-org#19870)