feat: add role management commands

[Davidonium]

Adds role and permission management under qcloud iam, enabling full CRUD for custom roles and permission discovery from the CLI. Roles control access to Qdrant Cloud resources and can be either system-managed (immutable) or custom (user-managed).

Commands

• qcloud iam role list -- List all roles in the account
• qcloud iam role describe -- Show details of a specific role, including its permissions
• qcloud iam role create -- Create a new custom role
• qcloud iam role update -- Update an existing custom role's name or description
• qcloud iam role delete -- Delete a custom role
• qcloud iam role assign-permission -- Assign a permission to a role
• qcloud iam role remove-permission -- Remove a permission from a role
• qcloud iam permission list -- List all available permissions

Additional changes

• Shell completion for role and permission IDs

[Davidonium]

This is repeated with #102.

I will handle the conflicts in this branch.