Use stricter C++ type conversions (#4357)

Now, implicit narrowing conversions are only used with wpi::Now(). This
also fixes clang-tidy warnings about C-style casts. For example:
```
== clang-tidy /__w/allwpilib/allwpilib/wpilibNewCommands/src/main/native/include/frc2/command/SwerveControllerCommand.inc ==
/__w/allwpilib/allwpilib/wpilibNewCommands/src/main/native/include/frc2/command/SwerveControllerCommand.inc:95:18: warning: C-style casts are discouraged; use static_cast/const_cast/reinterpret_cast [google-readability-casting]
  auto curTime = units::second_t(m_timer.Get());
                 ^
```
In that case at least, the cast was removed entirely since Get() already
returns a units::second_t.

wpilibcExamples/src/main/cpp/examples/DriveDistanceOffboard/cpp/commands/DriveDistanceProfiled.cpp

@@ -10,18 +10,18 @@ using namespace DriveConstants;
 
 DriveDistanceProfiled::DriveDistanceProfiled(units::meter_t distance,
                                              DriveSubsystem* drive)
-    : CommandHelper(
-          frc::TrapezoidProfile<units::meters>(
+    : CommandHelper{
+          frc::TrapezoidProfile<units::meters>{
               // Limit the max acceleration and velocity
               {kMaxSpeed, kMaxAcceleration},
               // End at desired position in meters; implicitly starts at 0
-              {distance, 0_mps}),
+              {distance, 0_mps}},
           // Pipe the profile state to the drive
           [drive](auto setpointState) {
             drive->SetDriveStates(setpointState, setpointState);
           },
           // Require the drive
-          {drive}) {
+          {drive}} {
   // Reset drive encoders since we're starting at 0
   drive->ResetEncoders();
 }

wpilibcExamples/src/main/cpp/examples/DriveDistanceOffboard/cpp/subsystems/DriveSubsystem.cpp

@@ -54,11 +54,11 @@ void DriveSubsystem::ResetEncoders() {
 }
 
 units::meter_t DriveSubsystem::GetLeftEncoderDistance() {
-  return units::meter_t(m_leftLeader.GetEncoderDistance());
+  return units::meter_t{m_leftLeader.GetEncoderDistance()};
 }
 
 units::meter_t DriveSubsystem::GetRightEncoderDistance() {
-  return units::meter_t(m_rightLeader.GetEncoderDistance());
+  return units::meter_t{m_rightLeader.GetEncoderDistance()};
 }
 
 void DriveSubsystem::SetMaxOutput(double maxOutput) {