Editor SideBar - Remember expande/colapse state

### Description

Would be nice, if in the editor on the sidebar for the dashboard, it could remember the collapse/extended state of pages and groups, as in Dashboard 1.0.

At the moment the default behaviour is always expanding, even if we just edit a widget (text box for example) after pressing `Done` it will expand all the Pages/Groups. Obviously, it should remain in the same place after editing a widget or group properties.

In case we have an elevated number of pages/group/widgets is cumbersome to always being scrolling to the where we were last time.

### Have you provided an initial effort estimate for this issue?

I am no FlowFuse team member

The issue does not name implementation files or tests. Start by locating the editor sidebar and comparing its behavior with Dashboard 1.0; done means page and group expand/collapse state remains unchanged after editing a widget or group, rather than resetting and requiring users to scroll back.

Written by the indexing model from the issue text.