hardware survey module

[0pcom]

• the survey module will retrieve system hardware resources (to the extent available at different user levels) with the ghw library
• a UUID will be generated to uniquely identify the running visor (either using the UUID library as its already used in the codebase or via a self-written random string generator)

Minimal struct to be encoded in survey results:

// The survey struct includes the minimal amount of information needed in the survey. As of now
// it is unclear whether we need further system info so it is dropped.
type Survey struct{
    UUID uuid.UUID
    PubKey cipher.PubKey
    Disks ghw.BlockInfo
    Product ghw.Product
    Memory ghw.Memory
}

• survey results will be written to ./local/system.json once upon startup and be exposed via the new dmsghttp server upon request by a whitelisted survey server (see authorization mechanism for inter-service communication via whitelisted PubKeys; for simplicity, it can be same public key as setup node or can be separate key)

[0pcom]

#1369