fix: instrumentation of ESM-imported mongoose

[JCMais]

Which problem is this PR solving?

Instrumenting mongoose while using ESM was crashing with:

TypeError: Cannot read properties of undefined (reading 'prototype')
    at MongooseInstrumentation.patch (/home/jcm/projects/opensource/opentelemetry-js-contrib/plugins/node/instrumentation-mongoose/build/src/mongoose.js:95:44)
    at MongooseInstrumentation._onRequire (/home/jcm/projects/opensource/opentelemetry-js-contrib/node_modules/@opentelemetry/instrumentation/build/src/platform/node/instrumentation.js:164:39)
    at hookFn (/home/jcm/projects/opensource/opentelemetry-js-contrib/node_modules/@opentelemetry/instrumentation/build/src/platform/node/instrumentation.js:227:29)
    at callHookFn (/home/jcm/projects/opensource/opentelemetry-js-contrib/node_modules/import-in-the-middle/index.js:29:22)
    at Hook._iitmHook (/home/jcm/projects/opensource/opentelemetry-js-contrib/node_modules/import-in-the-middle/index.js:150:11)
    at /home/jcm/projects/opensource/opentelemetry-js-contrib/node_modules/import-in-the-middle/index.js:18:41
    at Array.forEach (<anonymous>)
    at addHook (/home/jcm/projects/opensource/opentelemetry-js-contrib/node_modules/import-in-the-middle/index.js:18:10)
    at new Hook (/home/jcm/projects/opensource/opentelemetry-js-contrib/node_modules/import-in-the-middle/index.js:158:3)
    at MongooseInstrumentation.enable (/home/jcm/projects/opensource/opentelemetry-js-contrib/node_modules/@opentelemetry/instrumentation/build/src/platform/node/instrumentation.js:239:29)

Closes #2792

And contributes to #1942

Short description of the changes

This fixes it by checking the default export and also adds a test, that was failing before the fix:

[codecov]

Codecov Report

Attention: Patch coverage is 75.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 89.48%. Comparing base (32f41ee) to head (930196e).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...gins/node/instrumentation-mongoose/src/mongoose.ts	75.00%	2 Missing ⚠️

❌ Your patch status has failed because the patch coverage (75.00%) is below the target coverage (80.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2793      +/-   ##
==========================================
- Coverage   89.50%   89.48%   -0.02%     
==========================================
  Files         180      180              
  Lines        8719     8725       +6     
  Branches     1767     1771       +4     
==========================================
+ Hits         7804     7808       +4     
- Misses        915      917       +2     

Files with missing lines	Coverage Δ
...gins/node/instrumentation-mongoose/src/mongoose.ts	97.03% <75.00%> (-1.42%)	⬇️

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[pichlermarc]

I pushed a lint fix - overall the PR looks good, thank you for adding the test. 🙂
We can ignore the codecov complaint about the added lines not being covered (that's happening as the test that does cover is running out-of-process).