chore: impl Debug & Clone for Index params (#1808)

we don't really need these trait in lancedb, but all fields in `Index`
implement the 2 traits, so do it for possibility to use `Index`
somewhere

Signed-off-by: BubbleCal <bubble-cal@outlook.com>

rust/lancedb/src/index.rs

@@ -29,6 +29,7 @@ pub mod scalar;
 pub mod vector;
 
 /// Supported index types.
+#[derive(Debug, Clone)]
 pub enum Index {
     Auto,
     /// A `BTree` index is an sorted index on scalar columns.