Add search field to Connect Boards settings

Disconnecting boards from a high level board can be quite cumbersome. Adding a search box in the Connect Boards setting popup window would vastly improve the process of disconnecting boards.

We use a high level board to track all in-progress projects, which works well until we reach the enterprise limit of 60 connected boards. That is the point that we need to go and disconnect projects that are closing or closed. Scrolling through 60 boards in a tiny window is impractical.