feat: plot matrix proof of concept

[monfera]

Summary

Adds a proof of concept for a multilayered, trellised WebGL chart: plot matrix.

Shown functions:

• scatterplot matrix
• continuous heatmap
• density contours
• hexbins
• univariate density lookalike in the diagonals
• parallel coordinates
• interactions: axis brush, axis move, hover, range filter, splom axis wheel zoom
• per dimension single-range crossfiltering on the GPU
• focus (colorful) + context (greyscale)
• dark and light mode with adapting (reversing) heatmap palette

Details

Uses the kinGLy utility just like flamegraph.

More screenshots:

The proof of concept suffers from many weaknesses, for example hardwired everything; no integration with the charts API, theme and tooltip; untested, buggy GLSL shaders except the lines and points; resize glitches; temporary code for demo; super incomplete typescript etc.

Issues

Checklist

• The proper chart type label has been added (e.g. :xy, :partition)
• The proper feature labels have been added (e.g. :interactions, :axis)
• The :theme label has been added and the @elastic/eui-design team has been pinged when there are Theme API changes
• All related issues have been linked (i.e. closes #123, fixes #123)
• New public API exports have been added to packages/charts/src/index.ts
• Unit tests have been added or updated to match the most common scenarios
• The proper documentation and/or storybook story has been added or updated
• The code has been checked for cross-browser compatibility (Chrome, Firefox, Safari, Edge)
• Visual changes have been tested with all available themes including dark, light, eui-dark & eui-light

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[elastic-datavis]

Community pull request, @elastic/datavis please add the ci:approved ✅ label to allow this and future builds.