Updates node-addon-api

[vdeturckheim]

@simon-id , please add some tests when you have a way to reproduce the issue

[simon-id]

Potentially solves #82

[uurien]

This PR fixes the problems related with worker_threads and the waf. Added a test to check that it is working fine.
This PR also break the compatibility with node12, so next release should be a major release.

Here is a very short explanation about why this solves the problem:
nodejs/node-addon-api#711

Explanation: this example set the constructor static member of the class to a reference of the constructor function but if the addon is loaded multiple time (with worker_threads for example), the value is overwritten by a new reference in the new context. That makes this reference unusable to create new instances of this wrapped class from other C++ code and makes any code wanting to use this reference in another context crash.

[vdeturckheim]

🚀 🚀 🚀

[vdeturckheim]