feat: The Unique statistic in the summary bar should only count the number of non-null unique values

I have an idea for this project.

Why?

I've tried Notion, Airtable, and Baserow, they all don't count null values. I think this is because in most cases, we use Unique statistics to count the number of non-null unique values. If we want to count null values, we have separate null value statistics, don't we? So I suggest that APITable's unique statistics should not include null values. The expected result should be 2, not 3

What?

How?