feat(forma-36-tokens): Added JS export of all tokens with TS typings

[suevalov]

Purpose of PR

Adds index.js and index.d.ts generation for forma-36-tokens so tokens can be used in any CSS-in-JS library.

For example:

import styled from 'styled-components';
import tokens from '@contentful/forma-36-tokens';

const Item = styled.div`
   margin-top: ${tokens.spacingXl};
   color: ${tokens.colorGreenLight};
`;

All tokens are exported in a flat object with camelCase notation, which is more natural for JS and is more convenient to use with TS.

PR Checklist

• I have read the relevant readme.md file(s)
• All commits follow our Git commit message convention
• Tests are not required
• Tests are passing
• Storybook stories are not required
• Usage notes are updated
• Has been tested based on Contentful's browser support
• Doesn't contain any sensitive information

[m10l]

Nice!

[wichniowski]

🥇