Add a workflow to handle expired FOSSA invitations #27
Description
Invitations to join CNCF FOSSA eventually expire (I think it's around 72 hours) so we need a way of re-issuing invitations to Project Maintainers who don't get around to accepting the invitations first time round.
Add a /fossa-invite resend command that assigned staff and maintainers can run to get a new inviation sent out to them.