Microsoft code flow authentication won't work due to "code" query string parameter

When trying to do a code flow authentication (e.g. with [OneDrive, Step 2](https://dev.onedrive.com/auth/graph_oauth.htm#step-2-redeem-the-code-for-access-tokens)) there is a conflict in the query string parameter. Code flow requires a callback after authentication to a URL where it will pass back the authorization code using the query string parameter `code`. However, the function also requires the same parameter name to authenticate the caller to the Azure Function, unless you turn the `authLevel` to "anonymous".

It would be nice if the query string parameter name for the API key could be modified when needed.