[Icon] New icons types for Kibana Graph app

[dej611]

Is your feature request related to a problem? Please describe.
The Kibana Graph App is using the old font-awesome 4 package to render its icons.
We're considering the removal of such package and consider the migration of the current icon list to a mix of EUI icons + maki icons set (used by Map).

From the investigation it came out that there are only 2 missing icons which requires to be added from the EUI side: at (@) and key ( 🔑 ).

Edit: also the Google icon is missing

Describe the solution you'd like
Three new icons.

[MichaelMarcialis]

@dej611: I'll put together a PR this week that adds at and key icons to EUI's glyphs. Stay tuned.

For the Google icon you mention, we try to avoid adding logos to our icon library. It is suggested that you use a custom icon instead.