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