ggml webgpu: Clean up per-thread parameter buffer pool and job submission logic ...

ggml webgpu: Clean up per-thread parameter buffer pool and job submission logic (llama/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