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/libnt/native/cpp/NTCommandSelector.cpp

@@ -4,18 +4,21 @@
 
 #include "glass/networktables/NTCommandSelector.h"
 
+#include <fmt/format.h>
+#include <wpi/StringExtras.h>
+
 using namespace glass;
 
-NTCommandSelectorModel::NTCommandSelectorModel(wpi::StringRef path)
+NTCommandSelectorModel::NTCommandSelectorModel(std::string_view path)
     : NTCommandSelectorModel(nt::GetDefaultInstance(), path) {}
 
 NTCommandSelectorModel::NTCommandSelectorModel(NT_Inst instance,
-                                               wpi::StringRef path)
+                                               std::string_view path)
     : m_nt(instance),
-      m_running(m_nt.GetEntry(path + "/running")),
-      m_name(m_nt.GetEntry(path + "/.name")),
-      m_runningData("NTCmd:" + path),
-      m_nameValue(path.rsplit('/').second) {
+      m_running(m_nt.GetEntry(fmt::format("{}/running", path))),
+      m_name(m_nt.GetEntry(fmt::format("{}/.name", path))),
+      m_runningData(fmt::format("NTCmd:{}", path)),
+      m_nameValue(wpi::rsplit(path, '/').second) {
   m_runningData.SetDigital(true);
   m_nt.AddListener(m_running);
   m_nt.AddListener(m_name);