[Python] Support joinining tables with null columns

[lccnl]

Describe the enhancement requested

Hello,
currently pyarrow does not support performing a join between two tables if one has null columns even when it is not the joining column. For instance, this code will fail with pyarrow.lib.ArrowInvalid: Data type null is not supported in join non-key field:

import pyarrow as pa


tab1=pa.Table.from_arrays([pa.array([1,2]),pa.array([None,None])],names=['pk','null'])
tab2=pa.Table.from_arrays([pa.array([1,1]),pa.array(['a','b'])],names=['fk','some'])

tab1.join(right_table=tab2,keys='pk',right_keys='fk')

It would be nice to enable this!

Component(s)

C, Python

[Fokko]

We're also running into this at PyIceberg: apache/iceberg-python#1711