Streamline the template

[trbouma]

The initial template was too unwieldy so I streamlined into three parts. All of the conformity assessment requirements go in Part 2. Part 1 provides the context, and Part 3 provides detail on what might need to be done for the testing. If this works I will update the template

https://github.com/CIOSC/CAS-Digital-Credentials/blob/main/scheme/objects/objca-digital-credential.md