Add Gov-Client-Public-IP-Timestamp header to HMRC headers

[skodamarthi]

Is your feature request related to a problem? Please describe.
Refer to HMRC documentation here to know the info we need to send as part of this header: https://developer.service.hmrc.gov.uk/guides/fraud-prevention/connection-method/web-app-via-server/#gov-client-public-ip-timestamp

Describe the solution you'd like
Add a function to fetch timestamp when public IP address is collected using https://api.ipify.org as part of Gov-Client-Public-IP header and use that function to generate Gov-Client-Public-IP-Timestamp header needed by HMRC for fraud prevention.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.

[RiyaJohn]

@skodamarthi can I work on this issue?

[reubenae]

@RiyaJohn no need to ask, just go ahead and submit a PR

[RiyaJohn]

Cool, working on it, will raise a PR soon

[skodamarthi]

We have decided to close this issue for now as introducing this header in the library could cause issues to the existing customers, and adding this header using 3rd party APIs felt more of an unnecessary overhead than a benefit.