[BUG FIX] HTTP Trigger Functions with Multiple Output Bindings

[satvu]

Issue describing the changes in this PR

resolves #2079

Pull request checklist

• My changes do not require documentation changes
  • Otherwise: Documentation issue linked to 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

Currently, function metadata generation in both legacy and source-generation have special handling of HttpResponseData types in multiple output binding scenarios. Neither of these generators handle new types introduced in ASP.NET Core Integration (like IActionResult).

This PR introduces the following features:

• Introduction of HttpResponseOutputAttribute
  • Using this attribute on the intended HTTP response object will signal to generators to correctly generate function metadata
  • Explicit labeling will make the addition of new types easier and more regression-proof
• Handling of new attribute in source generator
• ASP.NET Core Integration package changes
• Introduction of TryGetHttpResponse<T>
• Refactoring to handle http response types in multiple output binding scenarios (where http is not a $return binding and has to be searched for inside of the output bindings list instead).
• Samples update

Not included:

• Fix in legacy generator (will follow up in separate PR).

[mattchenderson]

My main request is for changes to the sample so it can be leveraged in the docs.

[mattchenderson]

Just confirming - the sample changes have been dropped from this PR, correct? For docs, should I plan on an inline revision then?

[satvu]

Just confirming - the sample changes have been dropped from this PR, correct? For docs, should I plan on an inline revision then?

For now, yes - the sample with the docsnippet will be added after the SDK is released and we can update the sample app reference.

[fabiocav]

I've also pushed some changes to the middleware to help with some of the issues. Done a bit quickly, so the tests mentioned and a review, would be good.

Doc request no longer relevant