[Delfin UI] Support registration of centralized device manager.

[anvithks]

Issue/Feature Description: Provide support for registration of Centralized Device Managers from SODA Dashboard.

Why this issue to fixed / feature is needed(give scenarios or use cases): Delfin will be adding support for Centralized Managers. The same should be provided from the SODA Dashboard. How to reproduce, in case of a bug:

Other Notes / Environment Information: (Please give the env information, log link or any useful information for this issue)