Update `udp` source to use new `UdpFramed`

[LucioFranco]

Now that tokio-rs/tokio#1444 has been merged we can reduce the usage of double framed outputs in the udp source. This should allow us to use BytesDelimitedCodec just like how it is used in the tcp source.

cc @ktff

[ktff]

Yes, with an exception that we will need a wrapper around BytesDelimitedCodec which will map Wrapper::decode -> BytesDelimitedCodec::decode_eof

[LucioFranco]

@ktff not sure I follow what you mean there? Could you explain more?

[ktff]

@LucioFranco BytesDelimitedCodec::decode waits for newline before decoding a message. While udp source has one more message after that. Which stretches until eof.

[LucioFranco]

@ktff ah ok, would it make sense to change BytesDelimitedCodec to support reading up to a newline or a certain length say the end of the packet?

[ktff]

@LucioFranco Nope, since the size of the packet can vary, it would have to change it's behavior on eof which would break other code.

[binarylogic]

I'm not sure, but is this issue still relevant or should we close it?

[ktff]

It is, I'll implement it tomorrow.