[Embeddables] [Dashboard] [Lens] Provide an API for rendering custom legend items when Lens and other embeddables are rendered in non-edit mode

[andrew-goldstein]

Describe the feature:

Provide an API for rendering custom legend items when Lens and other embeddables are rendered in non-edit mode in an embeddable dashboard, as shown in the screenshot below:

Above: The Embedded Lens example (yarn start --run-examples) rendered in non-edit mode, in a Dashboard

Describe a specific use case for the feature:

The legend items adjacent to the Elastic Charts on the Security Solution Overview page, and throughout the app, are rendered as draggables:

Rendering all fields (including legend items) as draggables provides consistency throughout the Security Solution by allowing any field to be dragged to the Timeline to start or narrow an investigation, and to provide a common set of actions via a standardized hover menu.

An API that enables custom legend items to be rendered alongside Lens and other embeddables in a dashboard (in non-edit mode) would unlock the power of "dashboards everywhere" in the Security Solution, while preserving the consistency of the UX as it's implemented today.

[elasticmachine]

Pinging @elastic/kibana-app (Team:KibanaApp)

[drewdaemon]

Thank you for the detailed description of the issue! Closing in favor of #90724.

[markov00]

In order to provide better transparency of priorities, issues that will not be prioritized within the next 24 months are being closed.

Tracking request in Lens general improvements ice box #184459