V3 Polling: Only have one polling task.

[fmaximus]

When using multiple React Elements <Online />, <Offline />, and hooks with the same PollingConfig,
Polling should only happen once.

[cwise89]

This will be implemented in v3 as a singleton on the window object.

[geekskai]

@fmaximus You can take a look at this, this is the implementation of the reference v3 version https://github.com/geekskai/react-network-detect