Keep the legacy sidebar a supported option

[kirillrocks]

The old sidebar is still available today under Settings → General → Legacy features. Please keep it there, with no planned removal.

I gave Sidebar V2 a real chance. I used it every day for a week and did not let myself switch back. It still feels uncomfortable, and I am slower with it than with the old sidebar.

I am not asking to change Sidebar V2. I am asking for the legacy sidebar to stay a supported setting, so people who work better with it can keep using it.