Expose blockchain Id constants in web3data-js as public constants

[taylorjdawson]

Use Case:

Users want an easy to use library that is in English (or their native tongue)! So let us do away with these blockchain Ids and add human readable constants for use of use and sanity.

Requirements:

• Determine best convention for naming and exposing constansts

• The blockchain Id constants are already defined so just add them to the Web3Data class for ease of use

Acceptance Criteria:

• blockchain Id constants added to the Web3Data

Ex:

Web3data.BLOCKCHAIN_ID_ETHEREUM_MAINNET
const w3d = new Web3data(API_KEY, {
   blockchainId: Web3data.BLOCKCHAIN_ID_ETHEREUM_MAINNET
})