Possible missing roster push after contact invite

[mwild1]

As discovered by Ge0rG/tmolitor, it appears that a roster push may not be triggered on either/both sides of a contact invitation.

It probably needs to happen here: https://hg.prosody.im/prosody-modules/file/tip/mod_invites_register/mod_invites_register.lua#l105

[ge0rg]

It looks like the invitee gets a proper roster, but then again the inviter is on their roster already when creating the account, and they need to reconnect and login at that moment.

The inviter doesn't receive a roster push, but sees the initial presence from the invitee coming online as "directed presence".