Improvements and fixes

Cooperations get their own tab, the plants table lists each plant's components, and VPN services are restricted to organization admins and moderators.

• The plants table shows each plant's feed-in meters, inverters, combiner boxes, strings and sensors, with a legend for how their data is collected.
• Cooperations moved to their own tab on the organization page, with separate lists for outgoing and incoming cooperations, each searchable and paged.
• Members no longer see the VPN services on the organization page; only organization admins and moderators do.
• A VPN service with plants assigned can be deleted; the confirmation names the plants removed, and the plants table's VPN dialog can remove a plant.
• Adding a VPN service asks for its client address; editing one lets you upload a new WireGuard configuration file or replace its keys.
• Adding or editing a VPN service or a direct VPN rejects 0.0.0.0/0 and warns when a network overlaps another connection of the plant.
• Adding or editing a plant's direct VPN connection no longer asks for a gateway address; the connection is set up and checked without one.
• Opening a device that has not yet reported a status no longer fails.