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

wpiutil/src/test/native/cpp/leb128Test.cpp

@@ -14,23 +14,23 @@
 #include <stdint.h>
 
 #include <string>
+#include <string_view>
 
 #include "gtest/gtest.h"
 #include "wpi/SmallString.h"
-#include "wpi/StringRef.h"
 #include "wpi/leb128.h"
 #include "wpi/raw_istream.h"
 
 namespace wpi {
 
 TEST(LEB128Test, WriteUleb128) {
-#define EXPECT_ULEB128_EQ(EXPECTED, VALUE, PAD)         \
-  do {                                                  \
-    StringRef expected(EXPECTED, sizeof(EXPECTED) - 1); \
-    SmallString<32> buf;                                \
-    size_t size = WriteUleb128(buf, VALUE);             \
-    EXPECT_EQ(size, buf.size());                        \
-    EXPECT_EQ(expected, buf.str());                     \
+#define EXPECT_ULEB128_EQ(EXPECTED, VALUE, PAD)                \
+  do {                                                         \
+    std::string_view expected(EXPECTED, sizeof(EXPECTED) - 1); \
+    SmallString<32> buf;                                       \
+    size_t size = WriteUleb128(buf, VALUE);                    \
+    EXPECT_EQ(size, buf.size());                               \
+    EXPECT_EQ(expected, buf.str());                            \
   } while (0)
 
   // Write ULEB128