Allow creating Tokens from existing Figma files / structure

[six7]

We should allow reading existing Figma files for certain values and "importing" these as our tokens. For example check all borderRadii and use these as our borderRadius tokens.

Or check all Color Styles in a document - generate tokens from those (ideally so that they're attached with their StyleID)

Steps to completion:

• Color Styles Import
• Typography Styles Import
• Effects Styles import
• Add ability to configure what to import