Enabling Microsoft Authentication Library (MSAL) by default

[JohnSchmeichel]

Currently the Artifacts credential provider supports Azure Active Directory Authentication Library (ADAL) and Microsoft Authentication Library (MSAL). Due to the end of support announcement for ADAL the Artifacts credential provider will switch the default authentication library to MSAL, and later remove ADAL entirely from the code base.

There shouldn't be an impact to authentication and in many cases users should see an improved experience due to the follow MSAL features:

1. Silent authentication via the WAM Broker
2. MSAL token cache is enabled by default

To disable MSAL and continue using ADAL, set the following environment variable:

For Windows:

set NUGET_CREDENTIALPROVIDER_MSAL_ENABLED=false

For Linux/MacOS:

export NUGET_CREDENTIALPROVIDER_MSAL_ENABLED=false

Note: Use of ADAL and the environment variable above will be removed in future versions of the credential provider.