slice(gather(x, ind)) -> gather(x, slice(ind))

```mlir
%1078 = "stablehlo.gather"(%1077, %c_65) <{dimension_numbers = #stablehlo.gather, indices_are_sorted = false, slice_sizes = array}> : (tensor<1939xf32>, tensor<1939x1xi32>) -> tensor<1939xf32>
%1079 = stablehlo.slice %1078 [0:1] : (tensor<1939xf32>) -> tensor<1xf32>
```

Start from the StableHLO gather and slice example in the issue, then locate the compiler pass or rewrite machinery that handles these operations. Determine how the transformation should preserve the shown tensor shapes and gather attributes, and add or update a regression test demonstrating the rewrite from slice(gather(x, ind)) to gather(x, slice(ind)).

Written by the indexing model from the issue text.