Declarations that use interpolations with Props seem to be ignored

Emotion allows changing styles based on Props ( https://emotion.sh/docs/styled#changing-based-on-props ).
Right now declarations using this synthax seem to be ignored by the linter.

I think that for example the following cases should result in an error:

Example 1:
https://stylelint.io/user-guide/rules/declaration-block-no-duplicate-properties

```
const Button = styled.button`
color: ${props => (props.primary ? 'hotpink' : 'turquoise')};
color: ${props => (props.primary ? 'hotpink' : 'turquoise')};
`
```

Example 2:
https://stylelint.io/user-guide/rules/color-no-invalid-hex

```
const Button = styled.button`
color: ${(props) => (props.primary ? '#f00' : '#00')};
`;
```

该 issue 涉及 linter 忽略 styled-components 中使用 Props 插值的样式声明。查看 postcss-styled-components syntax plugin 中的 parser，了解它目前如何处理 template literal 插值。应添加测试用例，以验证使用 Props 时能够捕获重复属性和无效十六进制颜色规则。检查测试套件中现有的 styled-components 解析示例。

由索引模型根据 Issue 内容生成。