[Lens] Lens editor should be able to use the active data in configuration

[wylieconlon]

The Lens architecture is only able to use data tables while rendering, but not in configuration. This blocks some of the feature ideas that we have considered, such as:

• Determining the default color of the series
• Indicating the time interval in the configuration
• Showing nice labels for operations like Filters
• Showing error messages when the query isn't configured correctly

Implementation details

Datasources and visualizations both have needs for the "active data," so it should be managed by the editor frame. The editor frame already has a responsibility of building the expression which fetches data, so we could insert some additional code to store the most-recently fetched tables and then provide those tables to visualizations and datasources. Some information is going to be commonly needed, especially a list of any categorical keys that are part of the results. The Lens editor can extract the most-commonly-used metadata and pass it into configurations.

[elasticmachine]

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

[flash1293]

This will be done as part of #74509 (we need it anyway for CSV export)