The logging panel should never be empty

[FichteFoll]

When opening the logging panel for the first time (without messing with the settings), it is empty. You need to set log_server: [panel] in the settings first to have something show up there.

I suggest to automatically enable that setting temporarily when opening the log panel, because it is less confusing for users (and even maintainers) for debugging.

I would also wonder whether log_stderr should be enabled by default, but only do something when panel logging is enabled. It depends on whether language servers put a lot of garbage in there, I suppose. If that would be a problem, maybe setting this per language server in default_clients would be reasonable.