ggml webgpu: Clean up per-thread parameter buffer pool and job submission logic (#19772)
* Allow webgpu_buf_pool to resize if needed, remove inflight_threads, and replace inflight_threads with num_kernels for submission
* Run clang-format
* Keep track of num batched kernels that have not been submitted yet
* Run clang-format
* Increase buf pool max size
* Increase param buf pool init size
* Remove webgpu buf pool resizing
* Merge with master
* Add buffer pool growth
* Move buffer pool growth outside of lock
* Reduce max pool size to 32
* Run clang-format
* Only resize param buf pool