[Lens] Support for Histogram data type with sum, average

[wylieconlon]

The histogram data type is able to be used for some of the aggregations that Lens supports, specifically sum and average but not other metrics.

There are several places in the Lens code that need to be updated to support histograms:

• types.ts needs to get an updated DataType definition
• datapanel.tsx needs to include histogram as a type in a few places
• The indexpattern_suggestions.ts needs to update the getMetricColumn function
• The metrics.tsx file needs to update getPossibleOperationsForField, or maybe another way of allowing histograms on certain metrics but not others

[elasticmachine]

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