Add Ninsight Balances to bch-js

[christroutner]

This is a specific task that is associated with this top level task

The scope of this task is to port the BITBOX.Address.details() function to the Ninsight library in bch-js.

Porting the code should meet the following requirements:

• The code should follow the same pattern as the existing utxo() method, but should only use the POST call to the REST API. This should include api-doc documentation.
• A mainnet integration test should be included. You can follow the same pattern of the utxo mainnet integration test
• A testnet integration test should be included. You can follow the same pattern of the utox testnet integration test
• A unit test with mocking should be included. You can follow the same pattern of the utxo unit test

Acceptance Criteria

The bounty will be paid out upon successful acceptance of a Pull Request (PR) into this repository. The PR must include the following:

• Add a details() method to the Ninsight class library.
• The new method should include api-doc documentation.
• Add mainnet integration tests
• Add testnet integration tests
• Add unit tests