ggml-cpu: FA add GEMM microkernel (llama/19422)

ggml-cpu: FA add GEMM microkernel (llama/19422)

* ggml-cpu: FA add GEMM microkernel

* add guard for sizeless vector types

* fix case where DV % GGML_F32_EPR !=0

* move memset out of the loop

* move another memset out of the loop

* use RM=4 for arm

* simd_gemm: convert everything to int

* convert everything to size_t to avoid warnings

* fixup

* add pragma for ignoring aggressive loop optimizations