Added list_resource_providers function, which allows to retrieve
a list of Resource Providers filtering by UUID or parent UUID.
Added get_resource_provider function, which allows to retrieve an
specific Resource Provider by its UUID.
This feature depends on Nova Nested Resource Providers.
Depends-On: I4db74e4dc682bc03df6ec94cd1c3a5f5dc927a7bi
Change-Id: I6eb42b9a53c8001c5f14d4d1c9a98e060148ae21
Partial-Bug: #1578989
Co-Authored-By: Slawek Kaplonski <slawek@kaplonski.pl>