input_common/input_mapping: Add missing includes

Ensures that the class always sees the types it needs.

src/input_common/input_mapping.h

@@ -3,8 +3,14 @@
 // Refer to the license.txt file included
 
 #pragma once
+
+#include "common/param_package.h"
 #include "common/threadsafe_queue.h"
 
+namespace InputCommon::Polling {
+enum class InputType;
+}
+
 namespace InputCommon {
 class InputEngine;
 struct MappingData;