[Lens] Add collapse fn to table and xy chart

[flash1293]

Fixes #94619

This PR adds the ability to collapse the xy breakdown dimension or an arbitrary "row" in the table visualization.

If selected, the chart behaves as if the dimension doesn't exist, and its values are aggregated according to the selected function.

It would be theoretically possible to add a similar functionality to the partition chart but I don't see a large value for that because there are no common use cases where this would be necessary (and it's also no gap w.r.t. TSVB). Because of this IMHO such a feature would be more confusing than helpful for partition charts and it's better to push some possible exotic use cases into the text based languages.

Technical details

The collapse function is a separate expression function lens_collapse which takes a datatable and a list of columns to split by (the buckets) and a list of columns to collapse (the metrics) by a given function fn. All other columns are removed in the process. It's similar to overall_metric with the difference that the result isn't written to a separate column but instead replaces the existing metric column values and only produces a single row per group.

It is called by the supporting visualization before the table is passed to the actual visualization function). In case a collapse function is selected on a dimension, it is hidden for the visualization function.

Note: This PR overlaps with #131699 as it needs to migrate the datatable visualization off multi table to make it work.

[elasticmachine]

Pinging @elastic/kibana-vis-editors @elastic/kibana-vis-editors-external (Team:VisEditors)

[stratoula]

Joe this looks and it works great!
I only have a UX question, it is not so important, but I just want to discuss it

I have a chart like this (collapsed by sum)

I see that the breakdown has this invisible icon and no palette which makes sense. But the color of my chart is defined by the palette. As a user, my first instinct was to go to the metric and change the color of my series from there but I can't. I can only change the color by changing the palette and I dont have a lot of options here as the first palette color is automatically selected.

I find a bit confusing but maybe it is just me. Wdyt?

[flash1293]

I find a bit confusing but maybe it is just me. Wdyt

No, you are right, it should be possible to change the color like as for a regular metric, gonna adjust that.

[flash1293]

@stratoula Fixed, the color pickers is now enabled if the breakdown dimension is collapsed.

[stratoula]

Thank you Joe! This looks great 👏 LGTM!

The 5KB increase is due to the new expression right?

[kibana-ci]

💚 Build Succeeded

• Buildkite Build
• Commit: d8bc2c1
• Storybooks Preview
• Webpack Bundle Analyzer

Metrics [docs]

Module Count

Fewer modules leads to a faster build time

id	before	after	diff
lens	764	767	+3

Public APIs missing comments

Total count of every public API that lacks a comment. Target amount is 0. Run node scripts/build_api_docs --plugin [yourplugin] --stats comments for more detailed information.

id	before	after	diff
lens	451	452	+1

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
lens	1.1MB	1.1MB	-4.6KB

Page load bundle

Size of the bundles that are downloaded on every page load. Target size is below 100kb

id	before	after	diff
lens	27.5KB	32.5KB	+5.0KB

Unknown metric groups

API count

id	before	after	diff
lens	526	527	+1

async chunk count

id	before	after	diff
lens	10	11	+1

History

• 💚 Build #44653 succeeded 3a9740f
• 💚 Build #43988 succeeded da47187
• 💚 Build #43611 succeeded e5ccaa2
• 💔 Build #43583 failed 762f613
• 💔 Build #43098 failed d3d04c6

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

[ghudgins]

changes LGTM