Create better loading indicator experiences in serverside examples to enhance demonstration

[gabrielliwerant]

In the serverside-pagination example, we have some sample means of adding loading indicators. Loading indicators are a common and important part of the serverside experience, so we should have some better examples here so that other devs can work from good ideas, and we can keep full-fledged loading indicator options out of the core library (E.g. #958).

• Create more realistic, good UX loading indicator example(s) in the serverside-pagination example.

[jose-donato]

For example this? It hasn't the search problem referred in #958.

[gabrielliwerant]

@jose-donato In your screenshot, which is the action that causes the loading indicator to appear?

[jose-donato]

getData = () => { this.setState({ isLoading: true }); this.xhrRequest().then(res => { this.setState({ data: res.data, isLoading: false, count: res.total }); }); };

The getData function, the same it was before.