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

glass/src/lib/native/cpp/hardware/PWM.cpp

@@ -41,7 +41,7 @@ void glass::DisplayPWM(PWMModel* model, int index, bool outputsEnabled) {
 }
 
 void glass::DisplayPWMs(PWMsModel* model, bool outputsEnabled,
-                        wpi::StringRef noneMsg) {
+                        std::string_view noneMsg) {
   bool hasAny = false;
   bool first = true;
   model->ForEachPWM([&](PWMModel& pwm, int i) {
@@ -58,6 +58,6 @@ void glass::DisplayPWMs(PWMsModel* model, bool outputsEnabled,
     PopID();
   });
   if (!hasAny && !noneMsg.empty()) {
-    ImGui::TextUnformatted(noneMsg.begin(), noneMsg.end());
+    ImGui::TextUnformatted(noneMsg.data(), noneMsg.data() + noneMsg.size());
   }
 }