Fine-tune Board-Relation Columns: Customize Link Limits per Board Connection

In columns of connected boards, users should have the option to limit the linking of multiple items. When this option is activated, only one item can be linked. However, a limitation arises when multiple boards are connected to the same column. If a user needs to link an item from each connected board, they are unable to do so due to the global limitation. The proposed improvement suggests allowing users to customize the linking limitation on a per-connected-board basis. This means that if there are three connected boards in a column, users should be able to link only one item from each board, totaling three connected elements.