[Lens] Stacked to 100% option

[wylieconlon]

Stacking to 100% is not a single setting, but a combination of:

• Adding a new "bar stacked as percentage" and "area stacked as percentage" chart type
• Automatically selecting the Percent formatter
• Supporting the Other bucket on the Terms aggregation

[elasticmachine]

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

[wylieconlon]

This may be simplified if a pipeline function is added to support percentages: elastic/elasticsearch#51005

[flash1293]

It seems like this should be a layer-level setting.

Supporting the Other bucket on the Terms aggregation

This doesn't seem like a really nice addition, but a necessity for a "percentage mode". It looks like current visualize provides percentage mode with and without an "other bucket". Can we split this out into a separate issue and prioritize independently?

This may be simplified if a pipeline function is added to support percentages: elastic/elasticsearch#51005

This would require changes in esaggs, right? Does it make sense at the current point or should we just do the data modelling in the renderer?

For both automatic adddition of the "Other" bucket as well as using a different way to fetch the data I'm not sure how to properly pass the information about a "percentage mode chart" from the visualization to the renderer. Making this a pure visualization concern we would probably simplify implementation.

[flash1293]

When we implement this, we have to decide whether this is a layer level setting or a chart level setting.