metal : improve FA + improve MoE (#12612)

* ggml : FA with different K, V head sizes (CPU)

ggml-ci

* metal : add FA with HS=192

* metal : extend FA to support different K and V head sizes

ggml-ci

* metal : add FA vector kernels for heads K 192 and V 128

ggml-ci

* ggml : restrict op on other backends to equal head sizes

ggml-ci

* metal : optimize FA-vec kernel

ggml-ci

* metal : FA remove mq registers

* metal : improve MoE mul_mat_id condition

ggml-ci

* metal : fix comments + remove unnecessary addition

ggml-ci

* metal : avoid too much shared memory usage with mul_mat_id

ggml-ci

ggml/src/ggml.c

@@ -4369,7 +4369,7 @@ struct ggml_tensor * ggml_flash_attn_ext(
     }
 
     // permute(0, 2, 1, 3)
-    int64_t ne[4] = { q->ne[0], q->ne[2], q->ne[1], q->ne[3] };
+    int64_t ne[4] = { v->ne[0], q->ne[2], q->ne[1], q->ne[3] };
     struct ggml_tensor * result = ggml_new_tensor(ctx, GGML_TYPE_F32, 4, ne);
 
     float params[] = { scale, max_bias, logit_softcap };