Ping owner / the inviting user on join

[ConnysCode]

When XP joins a server, it should ping either the inviting user or the owner if audit logs are disabled.

Suggested by: 481099018676600853
Thread: 1151434356947173407

[crnvl]

i think it should only ping the inviting member. if that info cannot be fetched, the ping should be left out.
e.g. on servers of twitch streamers, there's no good reason to ping the streamer, who's most likely the owner, but doesn't really care about the server or the bots on it