response/result: re-export pub types

Re-exported types that should be exposed to users.
Re-exported types:
- ColumnSpec
- ColumnType
- CqlValue
- PartitionKeyIndex
- Row
- TableSpec

Note for reviewers: As mentioned in
#925 (comment),
we should not expose the `PreparedMetadata` structure. I believe
the same applies to `ResultMetadata`. That's why I decided not to
re-export them.

scylla/src/lib.rs

@@ -114,8 +114,15 @@ pub mod frame {
     }
 
     pub mod response {
+        pub use scylla_cql::frame::response::cql_to_rust;
         pub(crate) use scylla_cql::frame::response::*;
-        pub use scylla_cql::frame::response::{cql_to_rust, result};
+
+        pub mod result {
+            pub(crate) use scylla_cql::frame::response::result::*;
+            pub use scylla_cql::frame::response::result::{
+                ColumnSpec, ColumnType, CqlValue, PartitionKeyIndex, Row, TableSpec,
+            };
+        }
     }
 }