Fix Binary & Binary View Unparsing

[Sevenannn]

Which issue does this PR close?

N/A

Rationale for this change

Datafusion enforces an eager cast of value to Binary / BinaryView value in the logical plan where a comparison with binary value is presented. For example, in the following plan

Filter: value = CAST(Utf8("binary_value") AS Binary
However, when using unparser to convert the plan back to sql, where the sql will be sent to various query engine (e.g. DuckDB). the cast is not needed for the value, in the example above the value "binary_value", since the raw value can be directly used in SQL engines without casting to an engine specific dictionary type. Therefore, the plan can simply be rewritten into where value = 'binary_value'

What changes are included in this PR?

• Add function cast_to_sql, which directly pass inner_expr instead of cast inner_expr when casting to binary / binaryview / dictionary in the Expr::Cast, and keep the original casting logic in all other cases.
• Add a test for the change

Are these changes tested?

Yes

Are there any user-facing changes?

No

[alamb]

Thanks @Sevenannn -- this makes sense to me. I have some small suggestions but I don't think they are needed to merge this PR

[alamb]

I think you can write this more concisely with lit

Suggested change

	Expr::Cast(Cast {
	expr: Box::new(Expr::Literal(ScalarValue::Utf8(Some(
	"blah".to_string(),
	)))),
	data_type: DataType::Binary,
	}),
	Expr::Cast(Cast {
	expr: Box::new(lit("blah"))
	data_type: DataType::Binary,
	}),

You could also try to use https://docs.rs/datafusion/latest/datafusion/logical_expr/enum.Expr.html#method.cast_to but that requires a valid schema

[alamb]

🚀

[alamb]

Thanks @Sevenannn @phillipleblanc and @Jeadie