Fixed selected pane in items settings

Overview: Follow up on STRIPES-438, including comments.

Steps to repro:
1. Login to Folio test as diku_admin
2. Go to Settings > Items > Loan types or Material types
3. Switch to a different app - not a different settings page – e.g., Items app in the top navigation bar (to the left)
4. And then switch back to Settings

Expected results:
The second panes display the correct content by highlight of the correct Setting > Item > Loan types or Material types in the list – and you're back where you were, when switching back.
Alternative results: If you left Settings app when standing in the first pane Settings > Items, then after switching back again then the first choice in second pane should be displayed.

Actual results:
The navigation highlighting is lost. The secondary pane always highlights the first item in the list, even if the second one is really what's being displayed, and the primary pane – the list of apps with settings – is missing a highlight altogether.