feat: add ConstructorTraitTag to allow constructor return overridding

[legendecas]

Fixes: #1661

• Add docs.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 40.00000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 65.79%. Comparing base (a6213bb) to head (d07f9d7).
⚠️ Report is 30 commits behind head on main.

Files with missing lines	Patch %	Lines
napi-inl.h	40.00%	0 Missing and 3 partials ⚠️

Additional details and impacted files

@@ Coverage Diff @@## main #1670 +/- ##
=======================================
Coverage 65.79% 65.79% =======================================
Files 3 3 Lines 2146 2149 +3 Branches 715 716 +1 =======================================
+ Hits 1412 1414 +2 
Misses 162 162 - Partials 572 573 +1 

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[legendecas]

This does not work for InstanceMethod because there is a branch check enabled at https://github.com/nodejs/node/blob/main/src/js_native_api_v8.cc#L1028.

[greggman]

Thank you for working on this!

It's not clear from the comments if this is working yet. It sounds like maybe not?

I would suggest adding a few more tests

• Make a C++ class that inherits from Event, then pass it to a native event target

  constmyEvent=newCPPClassThatInheritsFromEvent('nameOfEvent');consttarget=newEventTarget();conste=awaitnewPromise(resolve=>{target.addEventListener('nameOfEvent',resolve,{once: true});target.dispatchEvent(myEvent);});assert(e===myEvent);

• Make a C++ class that inherits from EventTarget. Maybe sure you can use EventTarget's functionality

  consttarget=newCPPClassThatInheritsFromEventTarget();constevent=newEvent('foo');conste=awaitnewPromise(resolve=>{target.addEventListener('foo',resolve,{once: true});target.dispatchEvent(event);});assert(e===event);

[KevinEady]

This does not work for InstanceMethod because there is a branch check enabled at https://github.com/nodejs/node/blob/main/src/js_native_api_v8.cc#L1028.

Hi @legendecas , is there anything we can do to address this branch check? Is it absolutely needed?