Exclamation mark in circle icon

For the TSVB chart replacement we are also going to replace existing `fa` `font awesome` charts. We have one icon missing: an exclamation mark within a circle

<img width="200" alt="Screenshot 2019-07-15 at 16 46 16" src="https://user-images.githubusercontent.com/1421091/61225047-16833380-a720-11e9-9e3b-f64c122129e0.png">

It will be great to have this icon before 7.4 feature freeze