Resize desktop to window, instead of scaling

[manics]

Benefits:

• The whole window is used instead of just the central portion, making more efficient use of space
• The desktop is not scaled, so you don't end up with a high resolution desktop that's scaled down to fit the browser window

Example using a smallish browser window:
Before:

After:

[github-actions]

👈 Launch a binder notebook on this branch for commit c9795ea

I will automatically update this comment whenever this PR is modified

[yuvipanda]

This is a clear improvement! Eventually it would be useful to turn this into a dropdown option I think.

thanks @manics