Update device model to include a type field

[FirelightFlagboy]

We have multiple device type, and are working to introduce some more:

• Standard device
• Recovery device
• Shamir device
• Parsec Auth device

We would like to be able to differentiate the types of device.

We could add a field (like type) to identify the type of device.

Currently we rely on the untagged deserialization provided by serde to load each device type but we would like to provide that information upfront to the lib user.

Adding a type field, would also make serde more efficient at deserializing the devices since it can directly identify the type of device.

[FirelightFlagboy]

This concern the device certificate