Typescript support: useFela with props + css with varags params

[reinhard]

Description

As @marcneander pointed out in #676, the Typescript definition for useFela does not cover passing properties. Based on http://fela.js.org/docs/api/bindings/useFela.html this PR contains following improvements:

• passing props to useFela
• passing style as varargs to the css function

Example

See https://github.com/Indoqa/indoqa-react/blob/feature/usefela-with-props/packages/style-system-demo/src/fela/FelaHookSamples.tsx for all supported useFela usages.

// your code 

Packages

List all packages that have been changed.

Versioning

None / Patch / Minor / Major

Checklist

Quality Assurance

You can also run yarn run check to run all 4 commands at once.

• The code was formatted using Prettier (yarn run format)
• The code has no linting errors (yarn run lint)
• All tests are passing (yarn run test)
• There are no flow-type errors (yarn run flow)

Changes

If one of the following checks doesn't make sense due to the type of PR, just check them.

• Tests have been added/updated
• Documentation has been added/updated
• My changes have proper flow-types