ggml-webgpu: move from parameter buffer pool to single buffer with offsets (llama...

ggml-webgpu: move from parameter buffer pool to single buffer with offsets (llama/21278)

* Work towards removing bitcast

* Move rest of existing types over

* Add timeout back to wait and remove synchronous set_tensor/memset_tensor

* move to unpackf16 for wider compatibility

* cleanup

* Remove deadlock condition in free_bufs

* Start work on removing parameter buffer pools

* Simplify and optimize further

* simplify profile futures

* Fix stride

* Try using a single command buffer per batch

* formatting