Remember previously-selected group/entry on unlock

**Is your feature request related to a problem? Please describe.**
It's extremely common that I'll find myself wanting to look at the previous entry or group that I had selected in KeePassDX when unlocking it, especially if it's just auto-locked due to timeout, but every time it is unlocked it returns to the root and so I have to browse or search all over again. Which is frustrating and needlessly time-wasting.

**Describe the solution you'd like**
An option to remember the previously-selected group/entry, and automatically navigate back to it on unlock. If this option already exists and I've missed it... then it really needs a better location/name.

**Describe alternatives you've considered**
N/A

**Additional context**
N/A

Start by tracing the unlock flow and the navigation state for the selected group or entry. Determine how an optional remember-selection setting should behave across auto-lock and unlock, and verify that unlocking returns to the prior location when enabled without changing the default behavior.

Written by the indexing model from the issue text.