[clientpython] feat(contracts): add new ContractOutputType values for structured findings (#191)

[Sébastien MIGUEL (Seb-MIGUEL)]

Summary

• Add 13 new ContractOutputType enum values to support structured finding extraction beyond text and credentials
• New types: Username, Share, AdminUsername, Group, Computer, PasswordPolicy, Delegation, Sid, Vulnerability, AccountWithPasswordNotRequired, AsreproastableAccount, KerberoastableAccount
• These allow injectors to produce domain-specific findings instead of generic text output

Rationale

• Credentials should only represent reusable secrets (passwords, NTLM hashes, Kerberos keys)
• Kerberoasting/AS-REP roasting hashes are crackable material, not directly reusable credentials — they now have their own finding types
• Enumeration results (users, groups, shares, etc.) deserve specific types for proper filtering, display, and aggregation in the platform
• Vulnerability detections (Spooler enabled, LDAP signing not enforced, etc.) need a dedicated type separate from generic text

Backward Compatibility

No existing enum values were removed or renamed. This is purely additive.

Closes #191