[Lens] Support a formatter or format option which append "per second" "per minute" "per hour"

[wylieconlon]

Expected input

Users can configure this in addition to another formatter. They might need to indicate the suffix manually, or by selecting predefined suffixes. One of the predefined suffixes can be "auto", which would work with the auto date histogram to label the current time interval.

Expected output

There are three main uses:

1. Labeling the values in date histograms as representing a specific time period, such as "Sum of bytes per 3 hours"

2. Formatting data that already represents "per second" values, such as Apache metricbeat with a field called bytes_per_sec. We should be able to use the bytes formatter + per second suffix, to get 5Kb/s as an example. In this case the user needs to tell us the units.

3. Formatting a calculated rate, where the calculation is scaled by time. For example rate of sales per hour could be shown as "5,000/h" or "5,000 per hour"

Implementation notes

Because formatters are not composable in Kibana today, I think this should be implemented as a Lens-only feature. Formatters are part of the datasource, and these suffix options should be added to the datasource.

[elasticmachine]

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