Consider embedding icons

[ptmkenny]

At present, the icons in this audio player are loaded via a network request after the player has loaded. This can cause the player to fail in environments where access to the general Internet is restricted (for example, test servers). It also introduces network dependencies on third-party servers, which developers may want to avoid.

It seems this is because of the philosophy of the Iconify for React library:

Loads icons on demand. No need to bundle icons, component will automatically load icon data for icons that you use from Iconify API.

However, react-h5-audio-play only specifies 10 icons, so I think it would be more reliable to bundle all 10 icons with the player.