fix: close logging-channels when closing channels

[Nerixyz]

This is essentially a continuation of #4928 (or rather: I took the changes and applied them to the current code). Channels are now removed from the logger when they're destructed. If the app is being destroyed, they're not unregistered (they will be "unregistered" when the singleton is destructed). When a channel is destroyed (e.g. due to the user closing all tabs with the channel), its LoggingChannel, which holds the file handle, is destroyed. This also causes a stop-logging message to be inserted. Previously, that message was only appended when the app was closed. I'd argue that was a bug, since there weren't any messages logged.

I couldn't help myself but rename ChatterChatters to ChannelChatters, add a space to the stop message, and resolve some clang-tidy suggestions.