fix: Update persistent module to use simplified expression handling from PR #8

Author: lukekim

vortex-datafusion/src/lib.rs

@@ -6,13 +6,11 @@
 use std::fmt::Debug;
 
 use datafusion_common::stats::Precision as DFPrecision;
-use vortex::expr::stats::Precision;
+use vortex::stats::Precision;
 
 mod convert;
 mod persistent;
-pub mod vendor;
 
-pub use convert::exprs::ExpressionConvertor;
 pub use persistent::*;
 
 /// Extension trait to convert our [`Precision`](vortex::stats::Precision) to Datafusion's [`Precision`](datafusion_common::stats::Precision)