Use wpi::span instead of wpi::ArrayRef across all libraries (#3414)

- Remove ArrayRef.h
- Add SpanExtras.h for a couple of convenience functions

wpiutil/src/main/native/cpp/UDPClient.cpp

@@ -133,7 +133,8 @@ void UDPClient::shutdown() {
   }
 }
 
-int UDPClient::send(ArrayRef<uint8_t> data, std::string_view server, int port) {
+int UDPClient::send(span<const uint8_t> data, std::string_view server,
+                    int port) {
   // server must be a resolvable IP address
   struct sockaddr_in addr;
   std::memset(&addr, 0, sizeof(addr));