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/ScopedTracerTest.cpp

@@ -2,18 +2,20 @@
 // 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 <wpi/SmallString.h>
-#include <wpi/StringRef.h>
+#include <wpi/StringExtras.h>
 #include <wpi/raw_ostream.h>
 
 #include "frc/ScopedTracer.h"
 #include "frc/simulation/SimHooks.h"
 #include "gtest/gtest.h"
 
-wpi::SmallString<128> buf;
-wpi::raw_svector_ostream os(buf);
-
 TEST(ScopedTracerTest, Timing) {
+  wpi::SmallString<128> buf;
+  wpi::raw_svector_ostream os(buf);
+
   frc::sim::PauseTiming();
   {
     frc::ScopedTracer tracer("timing_test", os);
@@ -21,6 +23,6 @@ TEST(ScopedTracerTest, Timing) {
   }
   frc::sim::ResumeTiming();
 
-  wpi::StringRef out = os.str();
-  EXPECT_TRUE(out.startswith("	timing_test: 1.5"));
+  std::string_view out = os.str();
+  EXPECT_TRUE(wpi::starts_with(out, "	timing_test: 1.5"));
 }

wpilibc/src/test/native/cpp/shuffleboard/MockActuatorSendable.cpp

@@ -6,10 +6,12 @@
 
 #include "frc/smartdashboard/SendableRegistry.h"
 
+using namespace frc;
+
 MockActuatorSendable::MockActuatorSendable(std::string_view name) {
-  frc::SendableRegistry::GetInstance().Add(this, name);
+  SendableRegistry::GetInstance().Add(this, name);
 }
 
-void MockActuatorSendable::InitSendable(frc::SendableBuilder& builder) {
+void MockActuatorSendable::InitSendable(SendableBuilder& builder) {
   builder.SetActuator(true);
 }

wpilibc/src/test/native/cpp/shuffleboard/SuppliedValueWidgetTest.cpp

@@ -97,7 +97,7 @@ TEST_F(SuppliedValueWidgetTest, AddBooleanArray) {
 }
 
 TEST_F(SuppliedValueWidgetTest, AddRaw) {
-  wpi::StringRef bytes = "\1\2\3";
+  std::string_view bytes = "\1\2\3";
   m_tab->AddRaw("Raw", [&bytes]() { return bytes; });
   auto entry = m_ntInst.inst.GetEntry("/Shuffleboard/Tab/Raw");
 

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;
         }
       });