Add support for triggering popovers on hover, alongside the existing click or focus mechanisms.

[patpscal]

Is your feature request related to a problem? Please describe.

Currently, popovers cannot be triggered through hover events. However, some use cases, like desktop-oriented interfaces, can benefit from hover-triggered popovers to provide contextual information without requiring explicit action. This can improve usability by reducing friction for users needing quick insights before clicking.

Examples:

Data Visualization:
Showing details for data points when hovering over a chart. (Example from Grafana) This is already happening for Elastic visualizations.

Navigation:
Providing summaries or previews when hovering over link items. (Example from GitHub, VS)

How can Elastic benefit from this?

• Provides developers with more control over interaction patterns for popovers.

• Providing an overview on link hover before navigating could benefit users of the incoming entity-based model. Entities come with metadata attached, and having a quick summary before engaging could enhance the experience for some users. The same could be true for a host or a service. Currently, we do not have a pattern proposal yet for implementing this behavior, but we're exploring its application for some scenarios and we aim to facilitate a discussion to explore this possibility.

• This is already happening for Elastic visualizations. Instead of it being custom, we could allow it -> https://elastic.github.io/elastic-charts/storybook/?path=/story/annotations-lines--x-continuous-domain&globals=toggles.showHeader:true;toggles.showChartTitle:false;toggles.showChartDescription:false;toggles.showChartBoundary:false;theme:light

Basic guidelines that we could state for their effective use:

• Use hover popovers only for supplementary information, such as descriptions, explanations, or quick insights.
• Ensure the information is accessible elsewhere by providing an alternative way to access it (e.g., clicking through the trigger to access the complete information).
• Add slight delays to ensure intentional hover before displaying and to allow time for users to move the cursor to the popover without accidental dismissal.
• Content should be concise, digestible information without overwhelming the user.
• If an element is displaying a hover popover, it should always work this way. Example: if we assign this mechanism to, let's say, entities, users should expect the same behavior every time they check an entity link.

Desired timeline
Not urgent