Mechanism for devices to opt out of grid placement

[klauer]

(From a discussion with @ZLLentz)

• Name-based convention? e.g., hide devices that start with _
• Happi item metadata key? e.g., "hide_from_lucid_grid: True"
• Remove row/col values (stand=None) -> but this removes useful information

A variety metadata tag would make sense here, but they apply only to components.

[hhslepicka]

Neat idea! I think that a metadata key would be great as maybe you still want a good user-friendly name and as you also mentioned, info like stand could be holding useful information for other purposes.