GET dataset API should return public:LIST in ACL if available

When the GET dataset /gds/dataset API is called, gdsPermission=LIST is passed in query-param, available ACLs are not returned in the dataset.

It will be helpful to know, if the current dataset is accessible to public group (which can be eventually used by the depending applications). We can add the the ACL, in the returned dataset (if available):

"groups": { "public": "LIST" }