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/commands/pidcommand/ReplaceMePIDCommand.cpp

@@ -8,16 +8,15 @@
 // For more information, see:
 // https://docs.wpilib.org/en/stable/docs/software/commandbased/convenience-features.html
 ReplaceMePIDCommand::ReplaceMePIDCommand()
-    : CommandHelper(
-          frc2::PIDController(0, 0, 0),
-          // This should return the measurement
-          [] { return 0; },
-          // This should return the setpoint (can also be a constant)
-          [] { return 0; },
-          // This uses the output
-          [](double output) {
-            // Use the output here
-          }) {}
+    : CommandHelper{frc2::PIDController{0, 0, 0},
+                    // This should return the measurement
+                    [] { return 0; },
+                    // This should return the setpoint (can also be a constant)
+                    [] { return 0; },
+                    // This uses the output
+                    [](double output) {
+                      // Use the output here
+                    }} {}
 
 // Returns true when the command should end.
 bool ReplaceMePIDCommand::IsFinished() {