Azure.Sdk.Tools.RetrieveCodeOwners_1.0.0-dev.20211209.5

Simplify user check for codeowners parser (#2422)

We used to call the github users api but we often got 403 returned
due to rate limiting. So instead we are approximating the check
by checking for a slash in the name if there is one then we will
consider it to be a team instead of a user.