[2.4] Add warning when the same admin in project.yml has different role

[IsaacYangSLA]

Description

By design, provisioners can add clients or admins in project.yml and do provision to get additional client/admin startup kits. The certs and private keys of existing participants are kept the same so that there is no need to re-distribute those existing startup kits.

When the role of existing admin changes in project.yml, its cert/private key and thus the role in subject's unstructured_name, do not change. This causes confusion as provisioners may think a new set of cert/private key is generated.

This PR adds a warning during provisioning time so that provisioners know what to do to generate the new startup kits.

Types of changes

• Non-breaking change (fix or new feature that would not break existing functionality).
• Breaking change (fix or new feature that would cause existing functionality to change).
• New tests added to cover the changes.
• Quick tests passed locally by running ./runtest.sh.
• In-line docstrings updated.
• Documentation updated.

[yhwen]

LGTM

[IsaacYangSLA]

/build