Dynamic Dashboard: Improve error messages on dashboard cards.

[itsmeichigo]

We can even improve the error state screen further by displaying specific messages based on the errors.

E.g.: If we detect a timeout error, we can ask them to double-check the internet connection or hosting provider.

For errors coming from WPCom APIs, we can display relevant messages like Jetpack connection issues.

Internal discussion: pe5sF9-2PV-p2#comment-3718

[dangermattic]

Thanks for reporting! 👍