Added 2 new modules to manipulate volume types in OpenStack
* volume_type is used to create, delete and modify volume type
* volume_type_info is used to show volume_type details, including
encryption information
ci tests extended with additional role to test basic module behaviour
It is currently impossible to update is_public volume type attribute
as it is being changed to "os-volume-type-access:is_public" which is not
expected by api. Which expects just "is_public"
https://docs.openstack.org/api-ref/block-storage/v3/?expanded=update-a-volume-type-detail#update-a-volume-type
Which results in "'os-volume-type-access:is_public' was unexpected"
reply. I guess the change is required by openstacksdk or on the API side
Change-Id: Idc26a5240b5f3314c8384c7326d8a82dcc8c6171