Close confirmation only if multiple tabs

[chriswyatt]

Current Behavior

Currently, you only have a choice between there always being a prompt, and never a prompt. If the prompt is disabled, irregardless of whether there are multiple tabs open, the prompt will not appear, making it all too easy to accidentally close a long-running process.

Possible Solution

It would be nice to have the option to have the same behaviour as LXTerminal, where the prompt only appears if you have multiple tabs open.

Context

I often have a mix of windows with and without tabs, so it's easy to accidentally close multiple tabs without realising.

[stefonarch]

Similar to https://github.com/lxqt/qterminal/issues/173