Indicating external links in EUI

[gjones]

The Cloud docs team have expressed a wish for us to have a clear indication in the UI for when a link is going to an External site.

It's my opinion that this is something that should be better handled in EUI, perhaps as simple as an optional "opt-in" external prop on euiLink or an "opt-out" prop on euiLink whenever there's a target='_blank'. The latter would probably need a little more thought as it could have unforeseen consequences.

We discussed it briefly in the latest Design meeting and it seems as though this is something that other products have struggled with too.

Cloud devs have already put together a solution that can be used in the short term until we're able to get a longer-term solution into EUI that can ensure more consistency across all our products.

Cloud Example

Happy to discuss our options here and I believe @siemiatj would be willing to put together the PR if we can agree on an implementation.

Thanks!

Somewhat related: #2030

[ryankeairns]

Also somewhat related: #2020
^ contains discussion about adding a new prop for external links.

As an additional side note, the popout icon was recently updated as well:

[snide]

Marking this as a good first issue. This is still something someone a designer could do in a day. We probably just want to make a prop for EuiLink or check for target as @gjones suggested.