Upgrade to zohocrm/php-sdk-8.0 [2.x]

Problem/Motivation

Currently the module uses SDK version 2, while the latest version is SDK 8!

Please note the Zoho SDK Version vs. Version-Version chaos...

This is the latest:
https://www.zoho.com/crm/developer/docs/sdk/server-side/php-sdk.html

I'm pretty sure version 8 is incompatible to the current implementation so this might be a breaking change and maybe we should synchronize the version with the Zoho SDK Version for clarification and compatibility...

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes