fix: Left/right/outer joins should have nullable fields.

[carlyeks]

During a left, right, or outer join, some set of fields from input become nullable because they are optionally matched in the output. For a left join, the right fields become nullable. For a right join, the left fields become nullable. For an outer join, both sets become nullable.

This test fails with assertions enabled in Calcite code because the left join should have nullable right types.

[CLAassistant]

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