user role below "viewer"

Hi,

Since there seem to be some technical limitations when it comes to syncing between boards and user rights, it would be helpful to add an additional role that falls below the "viewer" role.

A role that doesn't permit anything, including viewing the board.

This would allow synchronization of comments/items between boards without giving full viewer access to parties which shouldn't have this access.

This could also be used for example to clean up the assignee dropdown, where if you exclude this "less-than-viewer" role from the available options, you prevent the assignee list from becoming cumbersome to use due to every user needing to be added to every single board to allow syncing items between them.

Tia!