pgl: Implement pgl::srv::Initialize

libraries/libstratosphere/source/pm/pm_shell_api.cpp

@@ -37,4 +37,8 @@ namespace ams::pm::shell {
         return ::pmshellBoostSystemMemoryResourceLimit(size);
     }
 
+    Result EnableApplicationExtraThread() {
+        return ::pmshellEnableApplicationExtraThread();
+    }
+
 }