Function rewrite_scalar_expression 

pub fn rewrite_scalar_expression(
    expression: &mut ScalarExpr,
    rewrite: &mut dyn FnMut(&mut ScalarExpr),
)

Visit one scalar-expression tree in post-order and rewrite each node once.

Query-owned callers that need scope-sensitive rewriting can use this entry point without duplicating the exhaustive ScalarExpr traversal.