[wpilibc] Use std::string_view instead of Twine (#3380)

Use fmtlib where needed for string formatting into std::string_view.

wpilibNewCommands/src/main/native/cpp/frc2/command/CommandBase.cpp

@@ -30,7 +30,7 @@ wpi::SmallSet<Subsystem*, 4> CommandBase::GetRequirements() const {
   return m_requirements;
 }
 
-void CommandBase::SetName(const wpi::Twine& name) {
+void CommandBase::SetName(std::string_view name) {
   frc::SendableRegistry::GetInstance().SetName(this, name);
 }
 
@@ -42,7 +42,7 @@ std::string CommandBase::GetSubsystem() const {
   return frc::SendableRegistry::GetInstance().GetSubsystem(this);
 }
 
-void CommandBase::SetSubsystem(const wpi::Twine& subsystem) {
+void CommandBase::SetSubsystem(std::string_view subsystem) {
   frc::SendableRegistry::GetInstance().SetSubsystem(this, subsystem);
 }