examples/basic: query_unpaged -> query_[single_page/iter]

In cases when we iterate over rows result, we make use of query_iter.
In other case, where we want to showcase the `Rows` structure,
we make use of `query_single_page`.

examples/basic.rs

@@ -1,6 +1,8 @@
 use anyhow::Result;
+use futures::TryStreamExt;
 use scylla::macros::FromRow;
 use scylla::transport::session::Session;
+use scylla::transport::PagingState;
 use scylla::SessionBuilder;
 use std::env;
 
@@ -49,11 +51,11 @@ async fn main() -> Result<()> {
         .await?;
 
     // Rows can be parsed as tuples
-    let result = session
-        .query_unpaged("SELECT a, b, c FROM examples_ks.basic", &[])
-        .await?;
-    let mut iter = result.rows_typed::<(i32, i32, String)>()?;
-    while let Some((a, b, c)) = iter.next().transpose()? {
+    let mut iter = session
+        .query_iter("SELECT a, b, c FROM examples_ks.basic", &[])
+        .await?
+        .into_typed::<(i32, i32, String)>();
+    while let Some((a, b, c)) = iter.try_next().await? {
         println!("a, b, c: {}, {}, {}", a, b, c);
     }
 
@@ -65,17 +67,21 @@ async fn main() -> Result<()> {
         _c: String,
     }
 
-    let result = session
-        .query_unpaged("SELECT a, b, c FROM examples_ks.basic", &[])
-        .await?;
-    let mut iter = result.rows_typed::<RowData>()?;
-    while let Some(row_data) = iter.next().transpose()? {
+    let mut iter = session
+        .query_iter("SELECT a, b, c FROM examples_ks.basic", &[])
+        .await?
+        .into_typed::<RowData>();
+    while let Some(row_data) = iter.try_next().await? {
         println!("row_data: {:?}", row_data);
     }
 
     // Or simply as untyped rows
-    let result = session
-        .query_unpaged("SELECT a, b, c FROM examples_ks.basic", &[])
+    let (result, _paging_state) = session
+        .query_single_page(
+            "SELECT a, b, c FROM examples_ks.basic",
+            &[],
+            PagingState::start(),
+        )
         .await?;
     let rows = result.rows.unwrap();
     for row in rows {