Easier way to view hidden boards

[Talismanian]

Currently, you can only view hidden boards by specifically searching for them. This can make it hard to find a specific board in a list of them hidden. (Side note: documentation on how to find hidden boards is needed.)

A couple of ways of making this easier could be:

1. A toggle in the Settings menu that shows hidden boards
2. A search filter for hidden boards

Then, a ... menu option should be to unhide the board again.