Create heatmap graph from elasticsearch histogram mapping

[PhracturedBlue]

Describe the feature:
Elasticsearch 7.6 will include a histogram mapping type to store pre-aggregated data efficiently. It would be convenient to be able to directly graph this data as a heatmap in Kibana.

Describe a specific use case for the feature:
https://discuss.elastic.co/t/generate-heatmap-from-histogram-data/216734/3

Example data:

{ @timestamp: Jan 27, 2020 @ 05:57:44.837, aggregate: { values: [5, 10, 20, 50, 100], counts: [0, 5, 3, 8, 16]},
{ @timestamp: Jan 27, 2020 @ 05:47:44.829, aggregate: { values: [5, 10, 20, 50, 100], counts: [13, 6, 1, 0, 11]},
...

[PhracturedBlue]

This appears to be covered by:
#52426