EthernetPacketizer: do a size check on incoming bytestream

[fvalla-MTA]

An incoming bytestream can be less than 24 bytes, leading to exceptions when accessing its data (or allocating the vector for its payload). Perform a size check before trying to decode the bytestream and discard invalid incoming streams.

[fvalla-MTA]

This solves the following error seen sporadically when using libicsneo-socketcan-daemon with a RAD-Jupiter:

terminate called after throwing an instance of 'std::length_error'
  what():  cannot create std::vector larger than max_size()
[1]    14203 IOT instruction  sudo ./libicsneo-socketcan-daemon