vulkan: Use VK_EXT_shader_64bit_indexing to handle large mat_mul(_id) (#18678)

This fixes incoherent output in Llama-4-Maverick-17B-128E-PAB-Q8_0, which
has a mul_mat_id with an A matrix that's Q8_0 8192 x 5120 x 128.

This should work when the number of blocks in the A matrix is less than 2^32
(for mul_mat_vec or mul_mm_cm2), or for mul_mm I think the limit is like
2^32*LOAD_VEC_A elements.

- Divide batch_stride by QUANT_K earlier, so the block index calculation works in 32b.
- Each vk_pipeline_struct has a linked list of pipelines that will allow it to handle
variants. So far this change just adds a single use case for this, compiling with the
e64BitIndexingEXT flag.
- Use the 64b indexing variant when the A matrix is larger than maxStorageBufferRange.

64-bit indexing has some cost - around 3-5% in MoE models, so it's worth the effort
to avoid enabling it unconditionally.

ggml/src/ggml-vulkan/vulkan-shaders/mul_mmq.comp

@@ -189,13 +189,13 @@ void main() {
     const uint end_k = min(p.K, (ik + 1) * p.k_split);
 #endif
 
-    uint pos_a_ib = (
+    uint pos_a_ib =
 #ifdef MUL_MAT_ID
-        expert_idx * p.batch_stride_a +
+        expert_idx * (p.batch_stride_a / BK) +
 #else
-        batch_idx_a * p.batch_stride_a +
+        batch_idx_a * (p.batch_stride_a / BK) +
 #endif
-        ir * BM * p.stride_a + start_k) / BK;
+        (ir * BM * p.stride_a + start_k) / BK;
 #ifdef MUL_MAT_ID
     uint pos_b_ib = 0;
 #else