set alias for image list params, added sort param

[matthi4s]

I added alias/sentAs definitions to some parameters of the ImagesV2 getImages() function which was missing and also added the sort parameter. https://docs.openstack.org/api-ref/image/v2/index.html?expanded=list-images-detail#list-images

The sortKey and sortDir parameters are abstract and also used in the BlockStorageV2 API, but from what I could find they are not really supported there: https://docs.openstack.org/api-ref/block-storage/v2/?expanded=list-snapshots-with-details-detail#list-snapshots-with-details

They are supported in the backups method, but from what I could find, this is not implemented in this library: https://docs.openstack.org/api-ref/block-storage/v2/?expanded=list-backups-with-details-detail#list-backups-with-details
But they use the same alias there and the sort_key and sort_dir alias follow the naming scheme, so I think it's safe to change it in the abstract class.

[k0ka]

Surprisingly BlockStorage does use sortKey and sortDir.
I added fixes for it and tests.
You might add tests for sort and other fields