Supporting new VSCode theme items

[matthewjamesadam]

Hi @daylerees -- thank you for making Rainglow, I really enjoy it!

The theme colours for VSCode have gotten a bit out of date -- there are many new theme values, many of which Rainglow doesn't support, and now parts of the UI look out of place (see #41 for an example).

It would be great if we could amend the build scripts and data to support these new items, but I can't figure out where the actually come from. Is this something that is publicly accessible anywhere? If this project has been abandoned, would you be open to open-sourcing up the original theme values so the community can bring these up to date?

Thanks!