Lens use of partition charts

[wylieconlon]

📦 Meta issue for Lens project

Trying to organize the feedback that we've given about pie and treemap charts into one place

Minimum expectations:

• Tooltip scrollbar bug Partition style chart (pie, treemap, etc) tooltips cause scrollbars to appear. #596
• Legend for first layer to show category colors Partition charts with legend and tooltip #532
• Bug with click handlers onElementClick arguments for treemap are not the same as for pie #624
• Linked labels not being displayed Pie chart linked labels are being displayed in cut off way #633
• Bug with treemap Treemap in infinite loop when valueAccessor returns zero #642
• Treemap padding Treemap should also observe the fillLabel.padding setting #659
• Color contrast by luminance Partition: calculate relative luminance for text #606

Nice to have:

• Nested legend Nested terms aggregations in legend #223
• Better label placement - treemap Inconsistent placement of fillLabel  #599
• Labels per group in treemaps Improved category labels for treemap #611
• Bug in partition legend width Partition legend width is not considering legendMaxDepth #639
• Ability to hide numbers in linkLabel Pie charts should have a setting for hiding numbers from chart, but keeping in tooltip #634
• Tooltip to show field + value Partition charts with legend and tooltip #532 Piechart tooltip shows field names #623
• Better label placement - sunburst Inconsistent placement of fillLabel  #599
• Tiny slices should be grouped during hover Pie/sunburst chart - discussion about small slices #381
• Show hovered value on legend Partition charts with Legend support doesn't work with showLegendExtra #638

For developer friendliness:

• Color theming Partition charts don't accept theming via color array #610

[monfera]

@wylieconlon upon today's release of #652, I split one row and checked a couple of boxes in the Description todo list, as the PR didn't address everything (can't be marked Closed)