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

wpiutil/src/test/native/cpp/HttpWebSocketServerConnectionTest.cpp

@@ -12,7 +12,7 @@ class HttpWebSocketServerConnectionTest
     : public HttpWebSocketServerConnection<HttpWebSocketServerConnectionTest> {
  public:
   HttpWebSocketServerConnectionTest(std::shared_ptr<uv::Stream> stream,
-                                    ArrayRef<StringRef> protocols)
+                                    ArrayRef<std::string_view> protocols)
       : HttpWebSocketServerConnection{stream, protocols} {}
 
   void ProcessRequest() override { ++gotRequest; }