[ARM VFS] 404 returned when trying to fetch the contents of .csproj file

Unable to load the content of `.csproj` file from arm vfs api. It returns a status of 404 even when the file exists.

You can repo this using the following steps,
> Go to aka.ms/ibizafication
> Open the Preview experience from the banner

> Go to App Files from the menu and select `extensions.csproj` from the file dropdown.

Note: The file content can be accessed through the Kudu site

Connected Issue - https://github.com/Azure/Azure-Functions/issues/1506

Reproduce the 404 through the ARM VFS API using the linked preview experience and extensions.csproj, then compare it with the successful Kudu response. Trace the API handling for .csproj file requests; done means an existing .csproj file returns its contents instead of 404.

Written by the indexing model from the issue text.