fix(cli-service): catch exception if "copy to clipboard" fails (issue #3476)

[jonaskuske]

As explained in issue #3476 , clipboardy throws an exception on some platforms, notably Windows Subsystem for Linux. This results in an unhandledPromiseRejection when using the --copy option.
As of right now this is just very annoying, but those rejections are deprecated and will completely stop the process in the future and so forth – you know the drill.

To prevent this I changed the copying to use writeSync() and wrapped it in a try catch-block. This also means we only log (copied to clipboard) now if copying was actually successful.

I also added a tip to the docs, it looks like this:

---

---

If you think this is unnecessary and we can just fail silently without mentioning it somewhere, we can also revert this commit of course :)

[jonaskuske]

By the way, it should be possible to get support for WSL upstream into clipboardy (by detecting WSL and piping to clip.exe) and I'll try to land that once I have time. Still, the error handling on our side is needed imo.