Improvements and fixes

Remote access to a plant now survives a move of its on-site agent. For connections Mirox hosts, OpenVPN is now suggested instead of WireGuard.

• Remote access to a plant survives a move of its on-site agent: the address stays the same and the agent reconnects by itself.
• For plants whose remote access Mirox hosts, OpenVPN is now suggested instead of WireGuard, and each option explains the reason.
• A half-finished VPN wizard is now kept as a draft and restored when it reopens for the same plant.
• A site connection can now be given its own name when it is added or edited, instead of the suggested one.