Added an option to get the current vk instance

Signed-off-by: Fabian Sauter <sauter.fabian@mailbox.org>

src/Manager.cpp

@@ -458,4 +458,10 @@ Manager::listDevices() const
     return this->mInstance->enumeratePhysicalDevices();
 }
 
+std::shared_ptr<vk::Instance>
+Manager::getVkInstance() const
+{
+    return mInstance;
+}
+
 }