Use std::string_view and fmtlib across all libraries (#3402)

- Twine, StringRef, Format, and NativeFormatting have been removed
- Logging now uses fmtlib style formatting
- Nearly all uses of wpi::outs/errs have been replaced with fmt::print() or
std::puts()/std::fputs() (for unformatted strings).
- A wpi/fmt/raw_ostream.h header has been added to enable
fmt::print() with wpi::raw_ostream

wpilibc/src/main/native/cpp/Watchdog.cpp

@@ -192,7 +192,7 @@ bool Watchdog::IsExpired() const {
   return m_isExpired;
 }
 
-void Watchdog::AddEpoch(wpi::StringRef epochName) {
+void Watchdog::AddEpoch(std::string_view epochName) {
   m_tracer.AddEpoch(epochName);
 }