Restsharp version bump and migrations to latest restsharp changes

[EtiSandeep]

Description

One Line Summary

REQUIRED - Updated the RestSharp and other nuget packages to latest version and migrated the restsharp code to latest changes.

Details

Motivation

REQUIRED - The version of restsharp is very old and is preventing the users to update the restsharp version for dependent projects.

Testing

Manual testing

REQUIRED - Tested createNotification api to send message to Subscribed Users segment.

Checklist

Overview

• I have filled out all REQUIRED sections above
• PR does one thing
  • If it is hard to explain how any codes changes are related to each other then it most likely needs to be more than one PR
• Any Public API changes are explained in the PR details and conform to existing APIs

Testing

• I have personally tested this on my device, or explained why that is not possible

Final pass

• Code is as readable as possible.
  • Simplify with less code, followed by splitting up code into well named functions and variables, followed by adding comments to the code.
• I have reviewed this PR myself, ensuring it meets each checklist item
  • WIP (Work In Progress) is ok, but explain what is still in progress and what you would like feedback on. Start the PR title with "WIP" to indicate this.