Linkable Backups & Databases

[RMartinOscar]

Ability to link server1 first backup to server2 so it can be use to restore server2 without having to download or move backups.
Ability to link server1 s1_test db to server2 so it show on the panel (graphical only).

Those links can only be done by servers owners & admins
If the two servers have different owners either ask admin or create a request system (if we make the request system we could enable it even if the two servers are owned by the same user)

Owner of server1 makes a request to allow x access to server2 then both owner receive an email to confirm (kinda like ovh does it).
This request system could also be used to transfer servers from one panel to an other one