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_gui/src/main/native/include/HALProvider.h

@@ -10,19 +10,18 @@
 #include <functional>
 #include <memory>
 #include <string>
+#include <string_view>
 #include <vector>
 
-#include <wpi/StringRef.h>
-
 namespace halsimgui {
 
 class HALProvider : public glass::Provider<> {
  public:
-  explicit HALProvider(const wpi::Twine& iniName) : Provider{iniName} {}
+  explicit HALProvider(std::string_view iniName) : Provider{iniName} {}
 
   void DisplayMenu() override;
 
-  glass::Model* GetModel(wpi::StringRef name);
+  glass::Model* GetModel(std::string_view name);
 
   /**
    * Returns true if outputs are disabled.