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

simulation/halsim_ws_server/src/main/native/include/HALSimHttpConnection.h

@@ -6,6 +6,7 @@
 
 #include <cinttypes>
 #include <memory>
+#include <string_view>
 #include <utility>
 
 #include <HALSimBaseWebSocketConnection.h>
@@ -38,14 +39,13 @@ class HALSimHttpConnection
 
  protected:
   void ProcessRequest() override;
-  bool IsValidWsUpgrade(wpi::StringRef protocol) override;
+  bool IsValidWsUpgrade(std::string_view protocol) override;
   void ProcessWsUpgrade() override;
-  void SendFileResponse(int code, const wpi::Twine& codeText,
-                        const wpi::Twine& contentType,
-                        const wpi::Twine& filename,
-                        const wpi::Twine& extraHeader = wpi::Twine{});
+  void SendFileResponse(int code, std::string_view codeText,
+                        std::string_view contentType, std::string_view filename,
+                        std::string_view extraHeader = {});
 
-  void MySendError(int code, const wpi::Twine& message);
+  void MySendError(int code, std::string_view message);
   void Log(int code);
 
  private: