[Feature Request] expect_column_values_to_be_null should succeed for empty arrays

[ilkernator]

Is your feature request related to a problem? Please describe.
I'm currently leveraging dbt-expectations in a project that is supposed to compile Hive queries. However, in many cases, when there is a column of type 'array' or 'struct(array)', the expect_column_values_to_be_null.sql-test can be misleading as the array could be simply "empty", i.e. '[ ]', '[" "]', ...

Describe the solution you'd like
I've created two very basic "column_values_basic" macros in my project that work just perfectly. Basically, I'm using the array_contains() and the size(). Hive functions to assert the column is empty. So I wanted to share this with the community.

Describe alternatives you've considered
I haven't thought about an alternative to be honest, as the need was there for me. However, I tried to keep the new tests as simple as possible.

Additional context
n.a.

[clausherther]

Thanks for sharing this. FYI, we don't support hive and have no plans to add support for hive in the future.