Add support for styled-jsx

[eR1cccc3]

Which issue, if any, is this issue related to?

https://github.com/stylelint/postcss-css-in-js/issues/335

Is there anything in the PR that needs further explanation?

• Support styled-jsx syntax in jsx

const Button = props => (
  <button>
    {props.children}
    <style jsx>{`
      button {
        color: #999;
        display: inline-block;
        font-size: 2em;
      }
    `}</style>
    <style jsx>{`
      button {
        padding: ${'large' in props ? '50' : '20'}px;
        background: ${props.theme.background};
      }
    `}</style>
  </button>
)

PS: external styles already has been supported somehow.

• Add tests for all my use cases