[sim] Provide function that resets all simulation data (#4016)

Fixes #3867

hal/src/main/native/athena/mockdata/Reset.cpp

@@ -0,0 +1,5 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+extern "C" void HALSIM_ResetAllSimData(void) {}