Implement fmt::ensure (assert-like with formatted message) + fmt::tie

Arguments should be provided via fmt::tie() due to some limitations.
Allow to specify simple message (non-formatting) for plain ::ensure().
Remove redundant function for narrow error.

rpcs3/main.cpp

@@ -419,7 +419,7 @@ int main(int argc, char** argv)
 	}
 #endif
 
-	ensure(thread_ctrl::is_main());
+	ensure(thread_ctrl::is_main(), "Not main thread");
 
 	// Initialize TSC freq (in case it isn't)
 	static_cast<void>(utils::get_tsc_freq());