jooby-apt: add option to remove mvcMethod and returnType from route

[jknack]

Today:

{
      /** See {@link Controller1292#response() */
      app.get("/", this::response)
        .setReturnType(String.class)
        .setMvcMethod(Controller1292.class.getMethod("response"));
}

With: -Ajooby.mvcMethod=false and -Ajooby.returnType=false:

{
      /** See {@link Controller1292#response() */
      app.get("/", this::response);
}