[wpimath] Move unit formatters into units library (#5358)

wpimath/src/test/native/cpp/FormatterTest.cpp

@@ -7,7 +7,6 @@
 #include <fmt/format.h>
 
 #include "frc/fmt/Eigen.h"
-#include "frc/fmt/Units.h"
 #include "gtest/gtest.h"
 #include "units/velocity.h"
 

wpimath/src/test/native/cpp/UnitsTest.cpp

@@ -1420,7 +1420,7 @@ TEST_F(UnitContainer, cout) {
 }
 #endif
 
-#if !defined(UNIT_LIB_DISABLE_FMT)
+#if __has_include(<fmt/format.h>) && !defined(UNIT_LIB_DISABLE_FMT)
 TEST_F(UnitContainer, fmtlib) {
   testing::internal::CaptureStdout();
   fmt::print("{}", degree_t(349.87));