Add preferred_username to the list of msft token claims (#106511)

Author: olegoid

extensions/microsoft-authentication/src/AADHelper.ts

@@ -40,6 +40,7 @@ interface ITokenClaims {
 	tid: string;
 	email?: string;
 	unique_name?: string;
+	preferred_username?: string;
 	oid?: string;
 	altsecid?: string;
 	ipd?: string;
@@ -454,7 +455,7 @@ export class AzureActiveDirectoryService {
 			scope,
 			sessionId: existingId || `${claims.tid}/${(claims.oid || (claims.altsecid || '' + claims.ipd || ''))}/${uuid()}`,
 			account: {
-				label: claims.email || claims.unique_name || '[email protected]',
+				label: claims.email || claims.unique_name || claims.preferred_username || '[email protected]',
 				id: `${claims.tid}/${(claims.oid || (claims.altsecid || '' + claims.ipd || ''))}`
 			}
 		};