Set default group for saving new logins

[wolftune]

Expected Behavior

I should be able to name the main group where logins are saved and have new ones go to that group.

Current Behavior

Each new entry keeps creating a group called "KeePassXC-Browser Passwords".

Side-note: I wish you'd move UI and naming stuff to "passphrase" instead of "password" in general.

Possible Solution

Related to #382 — but I don't want to have to choose a group every time, I'd like to just have a default group that saved items go to (probably with a preference of whether to ask which group vs use the default)

[varjolintu]

I'll add this option to the existing PR #396.

[varjolintu]

A following new setting has been added to the PR: