Icons for gathering not appearing in version browser

[andrewhead]

Describe the bug

The icons for "Open in notebook" and "Copy to clipboard" in the version browser are not appearing.

To Reproduce

Click on a variable or output, then click on "Gather to... Version Browser". You should be able to see that the icons are missing on the gather buttons.

Expected behavior

The icons should appear on the buttons, like so (screenshot taken from the version of gather currently hosted on BinderHub):

Additional context

This problem was probably introduced when gather started using Jupyter Lab libraries version >1.0 and the paths to the Jupyter icons changed. I already fixed the paths for the icons for the buttons in the Jupyter notebook toolbar in this commit, so we probably just need to point the CSS classes of the buttons in the version browser interface to the classes defined in that commit.

[rdrahul]

Can i take this up?

[andrewhead]

Hi @rdrahul thanks for pinging ^_^ Yeah, please do! I'm happy to review a PR if you want to put something together.

[andrewhead]

Solved by @rdrahul in #36 🎉