Enable log macros to work with no args (#4475)

This is enabled by the C++20 __VA_OPT__ feature.
Uses of "{}" format string were updated.
Some warning suppressions were required for older clang versions.
Also improve codegen of wpi::Logger::Log(), frc::ReportError(), and frc::MakeError();
these generate better and less redundant code if they use fmt::string_view for the
format string instead of templating on it.

wpilibNewCommands/src/main/native/cpp/frc2/command/CommandScheduler.cpp

@@ -119,7 +119,7 @@ void CommandScheduler::Schedule(Command* command) {
   }
 
   if (command->IsGrouped()) {
-    throw FRC_MakeError(frc::err::CommandIllegalUse, "{}",
+    throw FRC_MakeError(frc::err::CommandIllegalUse,
                         "A command that is part of a command group "
                         "cannot be independently scheduled");
     return;