Mobile / Fix board default scrolling position

[adjogima]

Context
When rendering a board the collapsible-columns controller tries to restore which columns the user left expanded. That state is saved in localStorage.
The controller goes through localStorage for each column (using an "expand-{board}-{column}" key) looking for a true value, then proceeds to expand the ones for which it did found a localStorage item, collapses all the other ones.

On mobile, that's only 1 column at a time, calling expand() on it scrolls it into view.
If no previously expanded column is found in localStorage, it'll default to Maybe, collapse all the other columns but doesn't calls expand() on the Maybe column, which is rendered expanded by default by the view.

Problem
On mobile it means if you visit a board for the first time, or even several times without ever manually expanding a column, no localStorage value is ever set, expand() is not called on any column, not scrolling any into view 👇

Fix
Call expand() when falling back on the Maybe column in mobile mode.