Custom layers support 

### Issue Type

Feature Request

### Source

source

### MCT Version

1.9.0

### OS Platform and Distribution

_No response_

### Python version

_No response_

### Describe the issue

```shell
MCT doesn't support quantizing custom layers at the moment.
```


### Expected behaviour

_No response_

### Code to reproduce the issue

```shell
N/A
```


### Log output

_No response_