[hal,wpilib] Rename "Test" robot mode to "Utility" (#8782)

The "Utility" name better matches its intended generic use case and
avoids overloaded terminology with unit testing (e.g. the need to name
the opmode annotation `@TestOpMode`).

The driver station will also be updated to reflect this change.

wpilibcExamples/src/main/cpp/examples/RapidReactCommandBot/cpp/Robot.cpp

@@ -45,12 +45,12 @@ void Robot::TeleopInit() {
 
 void Robot::TeleopPeriodic() {}
 
-void Robot::TestInit() {
-  // Cancels all running commands at the start of test mode.
+void Robot::UtilityInit() {
+  // Cancels all running commands at the start of utility mode.
   wpi::cmd::CommandScheduler::GetInstance().CancelAll();
 }
 
-void Robot::TestPeriodic() {}
+void Robot::UtilityPeriodic() {}
 
 #ifndef RUNNING_WPILIB_TESTS
 int main() {