feat: 128 bit UUIDs for client & device auth IDs

[cococry]

Summary

Added 128 bit client-generated IDs for user authentication and device authentication identifiers. RAND_bytes from OpenSSL is used for the random generation. The Protocol header and envelope data now serialize/deserialize 128 bit IDs instead of the temporary 32 bit integer IDs. The routing hashmap in faithd now keys by the 128 bit structure instead of a simple uint32_t.

client_id_t and device_id_t are now typedefed as:

typedef struct {
  uint8_t bytes[FAITH_CLIENT_ID_SIZE];
} client_id_t;

typedef struct {
  uint8_t bytes[FAITH_DEVICE_ID_SIZE];
} device_id_t;

Testing

Describe how you tested this change.

• scripts/check.sh passes locally
• CI passes for this pull request