[hal,wpilib] Rename FPGA clock to monotonic clock (#8672)

- Remove status return from HAL level (clock getting should never fail)
- Remove 32-bit timestamp expand function
- Make monotonic_clock.hpp (formerly fpga_clock.hpp) header-only and
move to root hal include directory

simulation/halsim_gui/src/main/native/cpp/DriverStationGui.cpp

@@ -1333,8 +1333,7 @@ void FMSSimModel::Update() {
 
   double matchTime = HALSIM_GetDriverStationMatchTime();
   if (!IsDSDisabled() && enabled) {
-    int32_t status = 0;
-    double curTime = HAL_GetFPGATime(&status) * 1.0e-6;
+    double curTime = HAL_GetMonotonicTime() * 1.0e-6;
     if (m_startMatchTime == -1.0) {
       m_startMatchTime = matchTime + curTime;
     }