Add Tektelic Mega ipk package

[brocaar]

I believe this could be the same as the Macro package script (https://github.com/brocaar/lora-gateway-bridge/blob/master/packaging/vendor/tektelic/kona-macro/package.sh) except:

Architecture: kona_mega

See also: https://forum.loraserver.io/t/ipk-file-not-available-for-tektelic-kona-mega-gateway/5007