fix: exports Api and NodeApi for NodeJS

[citizensas]

Review the exported members for the CommonJS format.
For NodeJS there will be the following exported members;

• Api - the Api class for NodeJS, previously known as NodeApi,
• NodeApi - same as above, keeping it for backward compatibility,
• ResponseHandler - an object containing success and failure callbacks,
• makeFetchCall - a function that makes the request bound with the ResponseHandler,
• default - exports Api, NodeApi, and ResponseHandler for backward compatibility purpose only.

Closes #1035.

[codecov]

Codecov Report

Merging #1037 (7ae2147) into master (b0b1107) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1037   +/-   ##
=======================================
  Coverage   84.01%   84.01%           
=======================================
  Files           1        1           
  Lines         269      269           
  Branches       61       61           
=======================================
  Hits          226      226           
  Misses         29       29           
  Partials       14       14           

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