Add NTP during installation time via install-config.yaml

Description

1. Proposed title of this feature request

Customer wants to add private NTP server during installation of ocp4.x via istall-config.yaml

2. What is the nature and description of the request?

Currently NTP can be added via ignition files but customer has  a need to add voia install-config.yaml 

3. Why does the customer need this? (List the business requirements here)

Customer has a special need to have this feature.

4. List any affected packages or components. - N/A