[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

hal/src/main/native/cpp/cpp/fpga_clock.cpp

@@ -1,32 +0,0 @@
-// 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.
-
-#include "wpi/hal/cpp/fpga_clock.hpp"
-
-#include <cstdio>
-#include <limits>
-
-#include "wpi/hal/HAL.h"
-#include "wpi/util/print.hpp"
-
-namespace wpi::hal {
-const fpga_clock::time_point fpga_clock::min_time =
-    fpga_clock::time_point(fpga_clock::duration(
-        std::numeric_limits<fpga_clock::duration::rep>::min()));
-
-fpga_clock::time_point fpga_clock::now() noexcept {
-  int32_t status = 0;
-  uint64_t currentTime = HAL_GetFPGATime(&status);
-  if (status != 0) {
-    wpi::util::print(
-        stderr,
-        "Call to HAL_GetFPGATime failed in fpga_clock::now() with status {}. "
-        "Initialization might have failed. Time will not be correct\n",
-        status);
-    std::fflush(stderr);
-    return epoch();
-  }
-  return time_point(std::chrono::microseconds(currentTime));
-}
-}  // namespace wpi::hal

hal/src/main/native/cpp/jni/HALUtil.cpp

@@ -473,17 +473,14 @@ Java_org_wpilib_hardware_hal_HALUtil_getTeamNumber
 
 /*
  * Class:     org_wpilib_hardware_hal_HALUtil
- * Method:    getFPGATime
+ * Method:    getMonotonicTime
  * Signature: ()J
  */
 JNIEXPORT jlong JNICALL
-Java_org_wpilib_hardware_hal_HALUtil_getFPGATime
+Java_org_wpilib_hardware_hal_HALUtil_getMonotonicTime
   (JNIEnv* env, jclass)
 {
-  int32_t status = 0;
-  jlong returnValue = HAL_GetFPGATime(&status);
-  CheckStatus(env, status);
-  return returnValue;
+  return HAL_GetMonotonicTime();
 }
 
 /*