Leave a clear line after spinner is stopped

[sbogomolov]

Currently after spinner is stopped it might leave behind the last symbol that was printed. This happens because '\b' is non-destructive in many terminal emulators. If '\n' is printed after spinner is done - the last printed symbol will remain printed (instead of an empty line). This happens because '\n' also happens to be non-destructive.

VS Code is one example of such terminal emulator.