Add callable and depth regions to output folder.

def _maybe_add_callable(data, out):
    """Add callable and depth regions to output folder.
    """
    callable_bed = dd.get_sample_callable(data)
    if callable_bed:
        out.append({"path": callable_bed, "type": "bed", "ext": "callable"})
    perbase_bed = tz.get_in(["depth", "variant_regions", "per_base"], data)
    if perbase_bed:
        out.append({"path": perbase_bed, "type": "bed.gz", "ext": "depth-per-base"})
    return out