Create branches specific to the SDK for each contract model.

[soonkuk]

Expected Behavior

• The SDK for each contract model is implemented on a different branch.
• The SDK for each contract model includes only the necessary common libraries(alias, base, key, utils) and contract-specific operations.
• The amount.js is excluded from currency operation folder and is included in the common library folder.
• Each SDK is published to the npm registry with a unique library name.
• A developer should selectively install each SDK library.

Actual Behavior

• The SDK for each contract model is implemented on a different repository.