[FEATURE]: Add `is_not_null_island` check

[tdikland]

Is there an existing issue for this?

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Problem statement

Geospatial data columns often contain POINT(0 0) to indicate that no known position exists. We essentially have the is_null problem for point geometries/geographies.

Proposed Solution

Write a new (geo)check that tests if a column of points does/doesn't contain the null island.

Additional Context

NULL island