Network pools

[dataclouder]

Add methods to create, update, and delete network pools. While the general purpose creation method can handle any type, we won't provide shortcuts or tests for VXLAN network pools, due to deprecated NSX-V backing. Also note that, while we can retrieve existing VXLAN network pools, its backing is not represented in the data structure.

• [x] Retrieval of transport zones
• [x] Creation with type GENEVE
• [x] Deletion of network pool
• [x] Retrieval of distributed switches
• [x] Creation with type VLAN
• [x] Creation with type PortGroup
• [x] Update of network pool
• [x] Complete test for all network pool types
• [x] Changelog items