fix(azure-functions-resource-detector): Update Azure Functions Detector to Consider WEBSITE_SKU

[JacksonWeber]

Which problem is this PR solving?

• It is possible for the Azure Functions detector to not detect the Azure Functions environment correctly in certain edge cases.

Short description of the changes

• There are some edge cases in which the FUNCTIONS_EXTENSION_VERSION may be undefined, in which case we should also check the WEBSITE_SKU for the value FlexConsumption to determine if we still may be running in an Azure Function.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.39%. Comparing base (dfb2dff) to head (6c91aff).
Report is 154 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2251      +/-   ##
==========================================
- Coverage   90.97%   90.39%   -0.59%     
==========================================
  Files         146      149       +3     
  Lines        7492     7525      +33     
  Branches     1502     1578      +76     
==========================================
- Hits         6816     6802      -14     
- Misses        676      723      +47     

Files	Coverage Δ
...tor-azure/src/detectors/AzureAppServiceDetector.ts	100.00% <100.00%> (+3.33%)	⬆️
...ctor-azure/src/detectors/AzureFunctionsDetector.ts	100.00% <100.00%> (ø)
...opentelemetry-resource-detector-azure/src/types.ts	100.00% <100.00%> (ø)
...opentelemetry-resource-detector-azure/src/utils.ts	100.00% <100.00%> (ø)

... and 53 files with indirect coverage changes

[maryliag]

I added a few nits :)

[hectorhdzg]

LGTM