Add support for strided index-select on Metal (#1909)

* initial implementation

* use correct index, but still not breaking like it should have...

* fix test

candle-metal-kernels/src/lib.rs

@@ -1067,8 +1067,13 @@ pub fn call_index_select(
     shape: &[usize],
     ids_size: usize,
     dim: usize,
+    contiguous: bool,
+    src_dims: &[usize],
+    src_strides: &[usize],
     input: &Buffer,
+    src_offset: usize,
     ids: &Buffer,
+    ids_offset: usize,
     output: &Buffer,
 ) -> Result<(), MetalKernelError> {
     let left_size: usize = shape[..dim].iter().product();
@@ -1090,8 +1095,11 @@ pub fn call_index_select(
             src_dim_size,
             right_size,
             ids_size,
-            input,
-            ids,
+            contiguous,
+            src_dims,
+            src_strides,
+            (input, src_offset),
+            (ids, ids_offset),
             output
         )
     );