Improve current editor line highlighting
Improve current editor line highlighting

The active editor line was previously highlighted with `nord2` instead
of `nord1` with a opacity of ~32% as background color and additionally
uses a border.
This has been changed to use `nord1` for both the background and border
to match Nord's design principles/guidelines.

GH-123

arcticicestudio/nord-visual-studio-code,arcticicestudio/nord-visual-studio-code