Vulkan Mixture of Experts (MoE) support (#7628)
* Finish Vulkan mul_mat_id implementation
* Add Vulkan sum_rows and div ops
* Fix MUL_MAT_ID matrix matrix shader
* Fix MUL_MAT_ID matrix vector shader dispatch size
* Fix MUL_MAT_ID matrix vector shader and dispatch code
* Update Vulkan CPU offload for MUL_MAT_ID
* Fix crash when using split mode none and setting a main GPU