Support unparsing implicit lateral `UNNEST` plan to SQL text

[goldmedal]

Is your feature request related to a problem or challenge?

After #13695, we can plan the implicit lateral unnest plan now. However, the generated logical plan can't be unparsed back to the SQL text.

If we tried to unparse the plan:

#[tokio::main]
pub async fn main() -> Result<()> {
    let ctx = SessionContext::new();
    ctx.sql("CREATE TABLE t (c1 array<int>)").await?.show().await?;
    ctx.sql("INSERT INTO t VALUES (ARRAY[1, 2, 3])").await?.show().await?;
    let sql = r#"select * from t, unnest(t.c1)"#;
    println!("SQL: {}", sql);
    let df = ctx.sql(sql).await?;
    let planned = df.into_optimized_plan()?;
    println!("Plan: {}", planned);
    let sql = plan_to_sql(&planned)?;
    println!("Plan to SQL: {}", sql);
    Ok(())
}

We will get the unsupported error

Error: This feature is not implemented: Unsupported operator: Subquery(<subquery>)

Describe the solution you'd like

Implement the unparsing behavior in Unparser::select_to_sql_recursively

Describe alternatives you've considered

No response

Additional context

No response