Add Rosetta Indexer

[LuttyYang]

This PR implements Rosetta's Indexer API(https://www.rosetta-api.org/docs/indexers.html), currently support Events and Search Endpoints

Test

Events Endpoints:

POST /events/blocks HTTP/1.1
Content-Type: application/json

{
    "network_identifier": {
        "blockchain": "Harmony",
        "network": "Testnet",
        "sub_network_identifier": {
            "network": "shard 0",
            "metadata": {
               "is_beacon": true
            }
        }
    },
    "offset": 1000,
    "limit": 5
}

---

HTTP/1.1 200 OK

{
    "max_sequence": 19020,
    "events": [
        {
            "sequence": 1000,
            "block_identifier": {
                "index": 1000,
                "hash": "0x7698a5a502089ecb37580897e3798f1c2425c07511fdde164f385d1e99252bf5"
            },
            "type": "block_added"
        },
        {
            "sequence": 1001,
            "block_identifier": {
                "index": 1001,
                "hash": "0xe086efe7374e3b43d4b50a2c9c88942f86539ff9f9f6bc82e84d5eeab4fce454"
            },
            "type": "block_added"
        },
        {
            "sequence": 1002,
            "block_identifier": {
                "index": 1002,
                "hash": "0xbebc5649ff1a6bb75c38da881fdff35796d8369b59831729d6cd29045ff70c02"
            },
            "type": "block_added"
        },
        {
            "sequence": 1003,
            "block_identifier": {
                "index": 1003,
                "hash": "0xdc068a9535201626dc602e4feccea32d4f1df9de044e1986b06a3e8fc413c7b2"
            },
            "type": "block_added"
        },
        {
            "sequence": 1004,
            "block_identifier": {
                "index": 1004,
                "hash": "0x6818d0326cfdc30b47172877010bc55251601bf79dbb3a83d6ba15258b231099"
            },
            "type": "block_added"
        }
    ]
}

Search Endpoints:

POST /search/transactions HTTP/1.1
Content-Type: application/json

{
    "network_identifier": {
        "blockchain": "Harmony",
        "network": "Testnet",
        "sub_network_identifier": {
            "network": "shard 0",
            "metadata": {
                "is_beacon": true
            }
        }
    },
    "operator": "or",
    "max_block": 5,
    "offset": 5,
    "limit": 5,
    "transaction_identifier": {
        "hash": "0x51207385e8327cc1405adc43049975557d1b07f205feebc89f4a2975df7819f4"
    }
}

---

HTTP/1.1 200 OK

{
    "transactions": [
        {
            "block_identifier": {
                "index": 9996,
                "hash": "0x7a863597cad374895c8aad5e1b09bc54ffa76097cb963cf8ad7c9dadb99865e7"
            },
            "transaction": {
                "transaction_identifier": {
                    "hash": "0x4573e600fc7ebf3d42116f89877edd751447bdb64f387070768118557748b409"
                },
                "operations": [
                    {
                        "operation_identifier": {
                            "index": 0
                        },
                        "type": "NativeTransfer",
                        "status": "success",
                        "account": {
                            "address": "one1l70tcs2u02ft54p4dupvunjcny54ry2wqzdmyu",
                            "metadata": {
                                "hex_address": "0xff9eBc415C7a92ba54356f02CE4E58992951914e"
                            }
                        },
                        "amount": {
                            "value": "10000000000000000000",
                            "currency": {
                                "symbol": "ONE",
                                "decimals": 18
                            }
                        }
                    }
                ],
                "metadata": {
                    "index": 0,
                    "size": "182.00 B"
                }
            }
        }
    ],
    "total_count": 1
}

[LeoHChen]

1. please make sure we cache the data to serve the request
2. please add upper bound limit to the request limit, so that the indexer API won't take too long to run

[LuttyYang]

@LeoHChen Added LRU cache, Currently cache 1000 requests within 5 minutes