Analyzer to detect missing ASP.NET Core integration registration

[surgupta-msft]

Issue describing the changes in this PR

resolves #1902

Pull request checklist

• My changes do not require documentation changes
  • Otherwise: Added documentation in the PR
• My changes should not be added to the release notes for the next release
  • Otherwise: I've added my notes to release_notes.md
• My changes do not need to be backported to a previous version
  • Otherwise: Backport tracked by issue/PR #issue_or_pr
• I have added all required tests (Unit tests, E2E tests)

Additional information

Additional PR information

[fabiocav]

Haven't reviewed the implementation, but we need to make sure this analyzer is part of the ASP.NET Core integration package.

[jviau]

I think we discussed having this analyzer only trigger if ConfigureFunctionsWorkerDefaults is present and ConfigureFunctionsWebApplication is not. Are we going with that approach or not?

I don't like the idea of having this analyzer trying to warn on the absence of something on IHostBuilder without something extra to indicate this is intended to be a function app and they are not configuring at as we expect.

[surgupta-msft]

I think we discussed having this analyzer only trigger if ConfigureFunctionsWorkerDefaults is present and ConfigureFunctionsWebApplication is not. Are we going with that approach or not?

I don't like the idea of having this analyzer trying to warn on the absence of something on IHostBuilder without something extra to indicate this is intended to be a function app and they are not configuring at as we expect.

(Providing a brief summary below about the things we discussed to avoid any confusion)

My understanding is we changed error to warning because absence of ConfigureFunctionsWebApplication() may not mean that the app is configured incorrectly and it won't work at all. The other thing we discussed which is tracked by a separate issue #1947 is the presence of both methods which can cause issues due to redundant calls. For that, we discussed that if we fix the redundant calls issue then we may not need any analyzer for that case at all.

For this exact thing - this analyzer only trigger if ConfigureFunctionsWorkerDefaults is present and ConfigureFunctionsWebApplication is not. I will setup some time to close on this.

Update - had an offline discussion. I have updated the code with this check. Thanks for catching this.