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/main/native/include/frc/smartdashboard/SendableRegistry.h

@@ -298,8 +298,8 @@ class SendableRegistry {
    * Data passed to ForeachLiveWindow() callback function
    */
   struct CallbackData {
-    CallbackData(Sendable* sendable_, wpi::StringRef name_,
-                 wpi::StringRef subsystem_, Sendable* parent_,
+    CallbackData(Sendable* sendable_, std::string_view name_,
+                 std::string_view subsystem_, Sendable* parent_,
                  std::shared_ptr<void>& data_, SendableBuilderImpl& builder_)
         : sendable(sendable_),
           name(name_),
@@ -309,8 +309,8 @@ class SendableRegistry {
           builder(builder_) {}
 
     Sendable* sendable;
-    wpi::StringRef name;
-    wpi::StringRef subsystem;
+    std::string_view name;
+    std::string_view subsystem;
     Sendable* parent;
     std::shared_ptr<void>& data;
     SendableBuilderImpl& builder;