adding machine scopes + machine secret to sdk (v3)

[Ben2W]

Machine Scopes, Secret Key, and Default Token TTL Support

This PR adds to the machine functionality in our Go SDK with three major features:

✨ New Features

🔗 Machine Scopes

Machines can now have access to other machines through scoped relationships:

type MachineWithScopedMachines struct {
    APIResource
    Machine
    ScopedMachines []*Machine `json:"scoped_machines"`
}

• Added ScopedMachines field to machine responses (array of machine IDs)
• Scoped machines never include secret keys to maintain security

�� Secret Key Support

Machines now return a SecretKey field when created:

type MachineWithScopedMachinesAndSecretKey struct {
    APIResource
    MachineWithScopedMachines
    SecretKey string `json:"secret_key"`
}

• Secret key is only included in create responses
• Not exposed in subsequent GET/UPDATE/LIST operations
• Maintains security by not exposing secret keys in scoped machine relationships

Default Token TTL

Added DefaultTokenTTL field to control token expiration:

type CreateParams struct {
    clerk.APIParams
    Name           string   `json:"name"` // Required for create
    ScopedMachines []string `json:"scoped_machines,omitempty"`
    DefaultTokenTTL *int64  `json:"default_token_ttl,omitempty"`
}

• Available as both request parameter (create/update) and response field
• Optional parameter with omitempty JSON tag

⚠️ Breaking Changes

Create Machine Name Parameter

// Before
CreateParams{Name: &stringPointer}

// After  
CreateParams{Name: stringValue}

Since the Name was required when creating machines, this was invalid. We also doubt anybody was using this function as it wasn't documented