[receiver/datadog] Add Datadog receiver (#5836)

Signed-off-by: John <john.dorman@sony.com>
Signed-off-by: John <dorman@overlooked.us>
Signed-off-by: John Dorman <john@boostchicken.dev>
Co-authored-by: Pablo Baeyens <pbaeyens31+github@gmail.com>
Co-authored-by: Gabriel Aszalos <gabriel.aszalos@gmail.com>
Co-authored-by: Juraci Paixão Kröhling <juraci.github@kroehling.de>
Co-authored-by: Sean Marciniak <30928402+MovieStoreGuy@users.noreply.github.com>
Co-authored-by: Alex Boten <alex@boten.ca>