Tech: GetAccountBalances

[andy-shi88]

Description

Implement GetAccountBalances endpoint.

Currently we have the skeleton code for GetAccountBalances available, but not implemented yet.

The Endpoint need to be able to provide account balance based on the addresses the client send.

Request {
    Addresses: [
        A,
        B,
        C,
    ]
}
Response {
    AccountBalances: [
        {
            A: 10000,
            B: 200100,
            C: 50,
        }
    ],

}

Breakdown

• Add Addresses field to GetAccountBalancesRequest
• Remove all other filed in GetAccountBalancesRequest
• At least 1 address is required in Addresses field.
• Return all account balances requested by the client.