I think we should add support for accessing theme's colors programmatically.

For instance let's take as an example the popular OneDark Pro theme, I'd like to access colors defined under tokenColors.

My use case: I'm making an extension that decorates some tokens, and I'd like them to have the same color that comments have in my theme, the problem is that the regex I use to find those tokens depends on some configurable value, so I cannot pre-compute it in advance and just put it in a .tmLanguage file.

It's already possible to somehow access colors defined under the colors key, via something like new vscode.ThemeColor ( 'activityBar.background' ), adding support for this sounds like a useful generalization to me.

What do you think?