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

ntcore/src/test/native/cpp/TestPrinters.cpp

@@ -126,7 +126,7 @@ void PrintTo(const Value& value, std::ostream* os) {
       *os << value.GetDouble();
       break;
     case NT_STRING:
-      *os << '"' << value.GetString().str() << '"';
+      *os << '"' << value.GetString() << '"';
       break;
     case NT_RAW:
       *os << ::testing::PrintToString(value.GetRaw());