fix: generate Query and Mutation mocks

While these types should not be used very often, it can
happen another mock references a `Query` or `Mutation` type.
Which means we'll declare a property value with `aQuery` or
`aMutation`

That's why we need to define those types

Fixes #42

src/index.ts

@@ -405,10 +405,6 @@ export const plugin: PluginFunction<TypescriptMocksPluginConfig> = (schema, docu
             // This function triggered per each type
             const typeName = node.name.value;
 
-            if (typeName === 'Query' || typeName === 'Mutation') {
-                return null;
-            }
-
             const { fields } = node;
             return {
                 typeName,