Use DataFusion unparser instead of sql_provider_datafusion/expr.rs

[phillipleblanc]

There is basic support for converting DataFusion expr to SQL as part of https://github.com/datafusion-contrib/datafusion-table-providers/blob/main/src/sql/sql_provider_datafusion/expr.rs

We should just be using the DataFusion unparser directly and remove this crate's version.

[hozan23]

@phillipleblanc I think we can close this issue ref: #99, #102