[Lens] Improve handling of partial data in date histograms

[wylieconlon]

Date histograms are rounded down in Elasticsearch which means that users will often have partial data for their data histograms. For example, if today is March 15th 2021 and I choose a "Last 1 year" time filter with 1 month as my date histogram interval, the date histogram will actually start on March 1st of the previous year, 2020, but due to the time filter the first 14 days of March will be excluded.

There are several potential ways that we can solve this problem:

• Allow the user to exclude the last partial bucket, which starts on March 1st 2021
• Allow the user to exclude all partial buckets, which excludes all the data from March 2020 and March 2021
• Default to a right-aligned date histogram, or allow the user to choose
• Instead of hiding partial buckets, indicate the partial data in all chart types including tables
• Update the X axis rendering so that partial bars are rendered at the correct size, without fixing other renderers like tables

I believe that none of these options is a 100% solution, but my personal preference is to allow both right-aligned and left-aligned date histograms. It might be best for backwards compatibility to keep the current left-aligned default.

[elasticmachine]

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

[ghudgins]

closing and will track this improvement in #7556