List should better not diaplay "No Data" when loading is true.

[Tarocch1]

What problem does this feature solve?

When “dataSource” of List is an empty array, there should be a "No Data" tip. But if it is loading, we are not sure if there is any data, the "No Data" tip shouldn't be displayed.

What does the proposed API look like?

<List
loading={true}
dataSource={[]}
renderItem={item => (
    //some code
)}
/>