Define icon to use in browser checks group card

[VikaCep]

Browser checks are using this icon. We should define whether we want to keep it or add a new one.

Originally posted by @ckbedwell in #862 (comment)

[VikaCep]

@majavojnoska I've been thinking on what icon to use for the new browser check group type. Here are a few options but I could really use your input/suggestions.

• globe (existing icon)
  

• monitor (existing icon)
  

• browser (we have to add it. docs on how to add a new icon)
  

• a different one?

For reference, the list of icons that we have available today https://developers.grafana.com/ui/latest/index.html?path=/story/docs-overview-icon--icons-overview

[majavojnoska]

None of these look good. And when I look into the other check types, none have the same line weight either. I'll try something custom.