SYCL: implement ggml_sycl_pool_vmm (llama/22862)

* SYCL: implement ggml_sycl_pool_vmm

* Add an option to bypass VMM with GGML_SYCL_DISABLE_VMM

* Clean up debugging logging

* document GGML_SYCL_DISABLE_VMM

* Multi-stream MoE optimization

* Revert "Multi-stream MoE optimization"

This reverts commit 938929c3f13a562ec67c59e87cc5d38595444cce.

* Update common.hpp

Co-authored-by: Neo Zhang <zhang.jianyu@outlook.com>

* Flip GGML_SYCL_DISABLE_VMM to GGML_SYCL_ENABLE_VMM

* add logging for GGML_SYCL_ENABLE_VMM when extension is not available (SYCL_EXT_ONEAPI_VIRTUAL_MEM macro)

* Apply suggestions from code review

Co-authored-by: Alexey Kopytko <alexey@kopytko.com>

* Apply suggestion from @sanmai

* Apply suggestion from @sanmai

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Co-authored-by: Neo Zhang <zhang.jianyu@outlook.com>