Add some group parameter to convolutions. (#566)

* Add some group parameter to convolutions.

* Avoid some unnecessary groups checks.

* Move the tensor convolution bits.

* Properh handling of groups.

* Bump the crate version.

* And add a changelog.

candle-core/examples/cuda_basics.rs

@@ -11,7 +11,7 @@ fn main() -> Result<()> {
     let device = Device::new_cuda(0)?;
     let t = Tensor::randn(0f32, 1f32, (2, 4, 96, 96), &device)?;
     let w = Tensor::randn(0f32, 1f32, (320, 4, 3, 3), &device)?;
-    let res = t.conv2d(&w, 1, 1)?;
+    let res = t.conv2d(&w, 1, 1, 1)?;
     println!("{res:?}");
     Ok(())
 }