Update measurements.json to v2 format, and add a helper to load and compare

[metachris]

Summary:

• Upgrade measurements.json to v2 data schema, which allows additional data fields besides the raw measurements (i.e. attestation_type. The v2 data schema is used at https://measurements.builder.flashbots.net
• Add MultiMeasurements - a helper to load a list of measurements, and compare provided measurements against them. Can load both new and previous data schema.
• Extends get-measurements with the capability to load a reference list of mesaurements and compare the current one to the known ones.
• Added a bunch of tests

---

Data schema v2

[
    {
        "measurement_id": "cvm-image-azure-tdx.rootfs-20241107200854.wic.vhd",
        "attestation_type": "azure-tdx",
        "measurements": {
            "4": {
                "expected": "1b8cd655f5ebdf50bedabfb5db6b896a0a7c56de54f318103a2de1e7cea57b6b"
            },
        }
    },
]

Data schema v1

{
    "azure-tdx-example": {
        "15": {
            "expected": "0000000000000000000000000000000000000000000000000000000000000000"
        },
    },
    "dcap-tdx-example": {
        "4": {
            "expected": "000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
        },
    }
}

---

Usage with get-measurements

# Load from URL
$ go run cmd/get-measurements/main.go \
    --addr https://redacted_instance_ip:7936 \
    --expected-measurements https://measurements.builder.flashbots.net

# Load from file
$ go run cmd/get-measurements/main.go \
    --addr https://redacted_instance_ip:7936 \
    --expected-measurements measurements.json

[MoeMahhouk]

maybe add a log.Error message here for better understanding what went wrong while debugging.

[metachris]

an error returned in the main function is still printed to the console. but still a valid point 👍

[Ruteri]

I'd remove the is