[Lens] use embeddable in editor

[drewdaemon]

Describe the feature:
We currently maintain two components for rendering Lens visualizations

• Embeddable — used in dashboard and solutions
• Workspace panel — used in the editor

At the end of the day, these two components both accept a Lens configuration, render it, emit user events, and respond to context changes (e.g. time range, visualization configuration, filters).

However, they are quite different implementations and this causes a maintenance burden over time.

For example, it took a lot of extra effort to get the User Messages system to work in both components.

The differences can lead to bugs, sometimes bad ones like #149667 which was only apparent in the Embeddable.

The way things are now also increases our testing surface since we can't depend on Lens to function the same outside the editor as it does inside.

We derived a lot of benefit from unifying the XY visualization expression renderers. I'm confident that we'd reap the same quality and stability benefits from unifying this part of the render stack as well.

[elasticmachine]

Pinging @elastic/kibana-visualizations (Team:Visualizations)

[stratoula]

Blocked by embeddables redesign. Let's assess then.

[markov00]

@dej611 is the new lens embeddable the answer to this?

[dej611]

No.
But this can be closed as the main editor will be replaced with 100% inline editing in the future.