[Dashboard Navigation] Add optional icons to links

[Heenawter]

Note
This issue was raised as a result of user testing.

Describe the feature:

Some users in our testing mentioned that the links panel did not stand out very much - it would be nice to be able to optionally add icons beside each link (either the dashboard or URL icon, depending on the link type) in the panel to draw attention to them + differentiate between the link types. This should (probably?) be a panel-level setting.

The LOE is small because I'm assuming we are only supporting icon types based on the link type - if we want to support custom icons, that would significantly impact the LOE.

[elasticmachine]

Pinging @elastic/kibana-presentation (Team:Presentation)

[nickpeihl]

What should be the default setting for icons?

IMO, the primary case for Links is supporting Dashboard links, and I think most users may only create Dashboard links. External links might not get created very often which limits the need to differentiate. Also, icons will take up more space on a screen which may not be wanted. So I think we could default to not showing icons and provide an EuiSwitch in the create/edit flyout to toggle icons for links.

Also, I think it just makes sense to only support the Eui icons dashboardApp and link, respectively for the initial MVP. If necessary, we can add support for custom icons in a future release.

[ThomThomson]

I'd say we should hold off on adding icons at all for the first few releases, until / unless we know that users want custom icons. Showing only Dashboard / External link icons doesn't give much additional information IMO.

[nickpeihl]

Maybe at least we should at least add support for the external icon for links that open in a new tab. This includes all external links and optionally dashboard links. #165771

That may help with some differentiation.

[nickpeihl]

I suspect users could make use of emojis in the link labels to fulfill this need.

🙇‍♂️ to @jsanz for providing this idea.

[Heenawter]

That's beautiful 🤩 Great idea, @jsanz!! Are we comfortable closing this issue then? cc @teresaalvarezsoler

[Heenawter]

Closing this for now - using emojis is a great (and simple!) way to add visual interest, and I'm not sure how much use a "Show link type" style toggle would actually get.... I worry that this would be redundant for most use cases, since dashboard linking will likely be much more common than external links.

We can re-open this based on user feedback + telemetry (which could be used to verify if my assumptions above are correct), if necessary.