Add obsolete tag to MsalServiceClientCredentialsFactory class

[ceciliaavila]

#minor

Description

This PR adds the obsolete tag to the MsalServiceClientCredentialsFactory class, so users opt to use one of the other factory classes depending on the type of authentication they use (ConfigurationServiceClientCredentialFactory, CertificateServiceClientCredentialsFactory, FederatedServiceClientCredentialsFactory, etc).

Specific Changes

• Update MsalServiceClientCredentialsFactory to add the Obsolete tag.

Testing

This image shows the obsolete tag added to the class.

[ceciliaavila]

Hi @tracyboehrer, this PR and a few others are failing with an error related to the private nuget feed. Let us know if there's anything we can do to help getting these merged.