Adds the foundation for managing tenant credentials, including:
- `TenantCredentialScore` for scoring credential-related operations.
- `TenantCredentialManager` trait for creating users.
- `CredentialMetadata` struct to store credential information.
- `CredentialData` enum to hold credential content.
- `TenantCredentialBundle` struct to encapsulate metadata and content.
This provides a starting point for implementing credential creation, storage, and retrieval within the harmony system.