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

wpilibc/src/test/native/cpp/simulation/AccelerometerSimTest.cpp

@@ -22,7 +22,7 @@ TEST(AcclerometerSimTests, TestActiveCallback) {
   bool lastValue = false;
 
   auto cb = sim.RegisterActiveCallback(
-      [&](wpi::StringRef name, const HAL_Value* value) {
+      [&](std::string_view name, const HAL_Value* value) {
         wasTriggered = true;
         lastValue = value->data.v_boolean;
       },

wpilibc/src/test/native/cpp/simulation/SimDeviceSimTest.cpp

@@ -2,8 +2,9 @@
 // Open Source Software; you can modify and/or share it under the terms of
 // the WPILib BSD license file in the root directory of this project.
 
+#include <string_view>
+
 #include <hal/SimDevice.h>
-#include <wpi/StringRef.h>
 
 #include "frc/simulation/SimDeviceSim.h"
 #include "gtest/gtest.h"
@@ -27,7 +28,7 @@ TEST(SimDeviceSimTests, TestEnumerateDevices) {
   bool foundit = false;
   SimDeviceSim::EnumerateDevices(
       "te", [&](const char* name, HAL_SimDeviceHandle handle) {
-        if (wpi::StringRef(name) == "test") {
+        if (std::string_view(name) == "test") {
           foundit = true;
         }
       });