ggml: allow casting between f32 and i32 (#15783)

* ggml: allow casting between f32 and i32

* fix cuda

* add vulkan

* fix CPU non-cont

* add non-cont test case

* add note

* extend test number range

* correct note

* add cont version for vulkan

ggml/src/ggml-cuda/convert.cuh

@@ -38,6 +38,8 @@ template<typename dst_t, typename src_t>
         return __float2bfloat16(float(x));
     } else if constexpr(std::is_same_v<src_t, nv_bfloat16>) {
         return __bfloat162float(x);
+    } else if constexpr(std::is_same_v<dst_t, int32_t>) {
+        return int32_t(x);
     } else {
         return float(x);
     }