Add raw_device for dx12, vulkan device

wgpu-hal/src/dx12/device.rs

@@ -283,6 +283,10 @@ impl super::Device {
         result
     }
 
+    pub fn raw_device(&self) -> &native::Device {
+        &self.raw
+    }
+
     pub unsafe fn texture_from_raw(
         resource: native::Resource,
         format: wgt::TextureFormat,

wgpu-hal/src/vulkan/device.rs

@@ -677,6 +677,10 @@ impl super::Device {
             },
         })
     }
+
+    pub fn raw_device(&self) -> &ash::Device {
+        &self.shared.raw
+    }
 }
 
 impl crate::Device<super::Api> for super::Device {