Add `IsNotNull` filter to join inputs if one side of join condition does not allow null

[andygrove]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.
I am running a query something like this:

SELECT * FROM foo JOIN bar ON foo.a = bar.b

The bar.b column does not allow null values but foo.a does. Rows in foo where a is null can never match any row in b for the inner join case with an equi-join condition foo.a = bar.b so we should add a filter when reading foo to filter out rows where a IS NULL before we perform the join.

Describe the solution you'd like
As described.

Describe alternatives you've considered
None

Additional context
None