The selection of layer based on the workspace

**Describe the bug**
I am trying to get the required layer from the workspace. But when I look to the code, there is only get_layer function based on the layer_name. According to the current version, the syntax looks similar to,

```python
cat.get_layer(layer_name)
```

What I purpose is,

```python
cat.get_layer(layer_name, workspace)
```

