[Feat] Develop ansible module for clusters in Nutanix Database Service

[bhati-pradeep]

Requirements:

• [x] Develop module for registering, updating and deregistering clusters in Nutanix Database Service

Todo:

• [x] Client SDK, get_spec()
• [x] Ansible spec & spec validator
• [x] Unit test, sanity test
• [x] Integration test
• [x] Documentation
• [x] Examples

[bhati-pradeep]

Feature added in v1.8.0 release