Requirement R4 - Prompt user for shared database password on startup

[pat672]

When the shared database password is configured to be stored in memory, prompt the user for the password on startup. This way we can guarantee that it will always be available when needed.

In the case that credential manager password storing has been implemented and in-memory passwords are used as fallback, then prompting the user for the password immediately on startup will make them aware that the fallback is active (and they might have to take action).

[emiros98]

The implementation of this, while not started, could borrow a lot from the implementation of #49.