fix: add isClassPrivateMethod() to esm-transformer

[nytamin]

Bug fix

This PR adds the check isClassPrivateMethod() to the detectESMFeatures topLevelAwait checks, to exclude private-hashtag-methods from bein considered top-level.

Background

I found a bug where I got the message path/to/file.js has both top-level await and export statements..., even though I had reduced the file in question to be simply:

export class MyClass {
  async #myMethod() {
    await Promise.resolve()
  }
}

Adding parent.isClassPrivateMethod() to the checks fixed the issue for me locally.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.23%. Comparing base (30924f0) to head (04c2924).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #300   +/-   ##
=======================================
  Coverage   87.23%   87.23%           
=======================================
  Files          23       23           
  Lines        7929     7931    +2     
  Branches     1214     1215    +1     
=======================================
+ Hits         6917     6919    +2     
  Misses       1005     1005           
  Partials        7        7           

Files with missing lines	Coverage Δ
lib/esm-transformer.ts	88.07% <100.00%> (+0.05%)	⬆️

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[robertsLando]

Thanks @nytamin for finding and reporting this! Closing as a duplicate of #307, which fixes the same bug by using Babel's parent.isFunction() alias. That alias covers ClassPrivateMethod plus every other function-like node, so no other function kind can slip through later. #307 also adds a unit test for this case.