Add meters to systems.

[haneslinger]

Systems should be able to have meters, same as properties.

Do this by adding the foreign key to meters, "systems".

There should be a constraint that a meter cant be on both a property and a systems.

Conversely, you would think that every meter should be on either a property or a system, but in the prod db, some meters dont have a property 🤔 more investigation is required.