Upstream Node-API implementation to facebook/hermes repo

[vmoroz]

This issue tracks the work to upstream the Node-API implementation to the https://github.com/facebook/hermes repo. We must complete the PR that is currently in the DRAFT mode: facebook#1377.

The remaining work:

• Extract the Node-API implementation into a separate folder.
• Provide the full set of Node-API unit tests adopted from the Node.js project.
• Make sure that the PR targets the static_h branch.