Need to include hidden files when using upload-artifact for .NET

Dues to a change in upload-artifact, hidden files are omitted unless `include-hidden-files: true` is included. This creates a problem for apps using .NET on the isolated worker model, as the build output will include a `.azurefunctions` folder, which is required for the app to work.

This should be captured in the README instructions to help users know to avoid the problem state and identify it when it occurs. The action should also warn if it finds that it is deploying to an app using .NET on the isolated worker model, and with this directory missing.

This is a subcategory of https://github.com/Azure/functions-action/issues/262. This leads to a silent failure that is hard to diagnose without knowledge of the upload-artifact issue.