Access auth contexts as public param. (#3379)

Author: mdaigle

src/Microsoft.Data.SqlClient/tests/ManualTests/SQL/Common/SystemDataInternals/FedAuthTokenHelper.cs

@@ -96,7 +96,7 @@ internal static object GetAuthenticationContextValue(SqlConnection connection)
 
             object databaseConnectionPoolObj = innerConnectionObj.GetType().GetProperty("Pool", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(innerConnectionObj);
 
-            IEnumerable authenticationContexts = (IEnumerable)databaseConnectionPoolObj.GetType().GetProperty("AuthenticationContexts", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(databaseConnectionPoolObj, null);
+            IEnumerable authenticationContexts = (IEnumerable)databaseConnectionPoolObj.GetType().GetProperty("AuthenticationContexts", BindingFlags.Public | BindingFlags.Instance).GetValue(databaseConnectionPoolObj, null);
 
             object authenticationContextObj = authenticationContexts.Cast<object>().FirstOrDefault();