Quality-of-life fixes

[zsol]

Over at https://github.com/zsol/vscode-glspc I made a bunch of fixes that helped me set up glspc for myself. I wanted to contribute back, but instead of opening a barrage of small issues, let me list them all in here. I'm curious if you're open to merging PRs for these:

• languageId defaults to an empty string which crashes the extension
• languageId is now an array
• when the server crashes (or I provide an incorrect command), the extension no longer crashes
• exceptions during language server shutdown no longer cause the extension to crash
• changing any settings now causes the server to be restarted
• restarting the server doesn't cause a new output pane to be opened
• all messages in the output pane now have timestamps and log levels
• there's now a dropdown that can be used to configure LSP traffic tracing (changing this doesn't cause the server to restart)
• there's no more popup when the server is started (instead, there's a status bar text that disappears after 5s)
• everything is configurable from the extension settings UI (except for initializationOptions)

[llllvvuu]

That's awesome, would be happy to take PRs!