Initialize FxID fields in GetBlock and GetBlockByHeight

[StephenButtolph]

Why this should be merged

FxIDs are used to specify how to parse a json struct. Currently they are left uninitialized as 11111111111111111111111111111111LpoYY.

How this works

Initializes the FxID fields like we do in in the avm.getTx API for avm.getBlock and avm.getBlockByHeight.

How this was tested

Before:

{
    "jsonrpc": "2.0",
    "result": {
        "block": {
            "parentID": "aku3My3D5NZvsSLhkw1orTEvmCn3GS1nDnFQhivbvfFFUxdLw",
            "height": 5,
            "time": 1680889438,
            "merkleRoot": "11111111111111111111111111111111LpoYY",
            "txs": [
                {
                    "unsignedTx": {
                        "networkID": 12345,
                        "blockchainID": "2eNy1mUFdmaxXNj1eQHUe7Np4gju9sJsEtWQ4MX3ToiNKuADed",
                        "outputs": [
                            {
                                "assetID": "2fombhL7aGPwj3KH4bfrmJwW6PVnMobf9Y2fn9GwxiAAJyFDbe",
                                "fxID": "11111111111111111111111111111111LpoYY",
                                "output": {
                                    "addresses": [
                                        "X-local18jma8ppw3nhx5r4ap8clazz0dps7rv5u00z96u"
                                    ],
                                    "amount": 299999999995000000,
                                    "locktime": 0,
                                    "threshold": 1
                                }
                            }
                        ],
                        "inputs": [
                            {
                                "txID": "oW48Xytve3bEfiUGaMLbqfPpxGojfrwvi32SVHqS5cLWJju7R",
                                "outputIndex": 0,
                                "assetID": "2fombhL7aGPwj3KH4bfrmJwW6PVnMobf9Y2fn9GwxiAAJyFDbe",
                                "fxID": "11111111111111111111111111111111LpoYY",
                                "input": {
                                    "amount": 299999999996000000,
                                    "signatureIndices": [
                                        0
                                    ]
                                }
                            }
                        ],
                        "memo": "0x",
                        "name": "HI",
                        "symbol": "HI",
                        "denomination": 1,
                        "initialStates": [
                            {
                                "fxIndex": 0,
                                "fxID": "11111111111111111111111111111111LpoYY",
                                "outputs": [
                                    {
                                        "addresses": [
                                            "X-local18jma8ppw3nhx5r4ap8clazz0dps7rv5u00z96u"
                                        ],
                                        "amount": 49463,
                                        "locktime": 0,
                                        "threshold": 1
                                    }
                                ]
                            }
                        ]
                    },
                    "credentials": [
                        {
                            "fxID": "11111111111111111111111111111111LpoYY",
                            "credential": {
                                "signatures": [
                                    "0xcfe2a011413cf60a8d343b4a6ebce55757c2818149550d9118868833d09739170aa91d123de6c658ac679e07bfd67ce2328deb64c8ef8955b9db49e9410c60dd01"
                                ]
                            }
                        }
                    ]
                }
            ]
        },
        "encoding": "json"
    },
    "id": 1
}

After:

{
    "jsonrpc": "2.0",
    "result": {
        "block": {
            "parentID": "aku3My3D5NZvsSLhkw1orTEvmCn3GS1nDnFQhivbvfFFUxdLw",
            "height": 5,
            "time": 1680889438,
            "merkleRoot": "11111111111111111111111111111111LpoYY",
            "txs": [
                {
                    "unsignedTx": {
                        "networkID": 12345,
                        "blockchainID": "2eNy1mUFdmaxXNj1eQHUe7Np4gju9sJsEtWQ4MX3ToiNKuADed",
                        "outputs": [
                            {
                                "assetID": "2fombhL7aGPwj3KH4bfrmJwW6PVnMobf9Y2fn9GwxiAAJyFDbe",
                                "fxID": "spdxUxVJQbX85MGxMHbKw1sHxMnSqJ3QBzDyDYEP3h6TLuxqQ",
                                "output": {
                                    "addresses": [
                                        "X-local18jma8ppw3nhx5r4ap8clazz0dps7rv5u00z96u"
                                    ],
                                    "amount": 299999999995000000,
                                    "locktime": 0,
                                    "threshold": 1
                                }
                            }
                        ],
                        "inputs": [
                            {
                                "txID": "oW48Xytve3bEfiUGaMLbqfPpxGojfrwvi32SVHqS5cLWJju7R",
                                "outputIndex": 0,
                                "assetID": "2fombhL7aGPwj3KH4bfrmJwW6PVnMobf9Y2fn9GwxiAAJyFDbe",
                                "fxID": "spdxUxVJQbX85MGxMHbKw1sHxMnSqJ3QBzDyDYEP3h6TLuxqQ",
                                "input": {
                                    "amount": 299999999996000000,
                                    "signatureIndices": [
                                        0
                                    ]
                                }
                            }
                        ],
                        "memo": "0x",
                        "name": "HI",
                        "symbol": "HI",
                        "denomination": 1,
                        "initialStates": [
                            {
                                "fxIndex": 0,
                                "fxID": "spdxUxVJQbX85MGxMHbKw1sHxMnSqJ3QBzDyDYEP3h6TLuxqQ",
                                "outputs": [
                                    {
                                        "addresses": [
                                            "X-local18jma8ppw3nhx5r4ap8clazz0dps7rv5u00z96u"
                                        ],
                                        "amount": 49463,
                                        "locktime": 0,
                                        "threshold": 1
                                    }
                                ]
                            }
                        ]
                    },
                    "credentials": [
                        {
                            "fxID": "spdxUxVJQbX85MGxMHbKw1sHxMnSqJ3QBzDyDYEP3h6TLuxqQ",
                            "credential": {
                                "signatures": [
                                    "0xcfe2a011413cf60a8d343b4a6ebce55757c2818149550d9118868833d09739170aa91d123de6c658ac679e07bfd67ce2328deb64c8ef8955b9db49e9410c60dd01"
                                ]
                            }
                        }
                    ]
                }
            ]
        },
        "encoding": "json"
    },
    "id": 1
}