Make ChainedTokenCredential private (#2440)

Author: chlowell

sdk/identity/azure_identity/src/chained_token_credential.rs

@@ -1,6 +1,8 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License.
 
+#![allow(dead_code)]
+
 use crate::credentials::cache::TokenCache;
 use crate::TokenCredentialOptions;
 use async_lock::RwLock;

sdk/identity/azure_identity/src/lib.rs

@@ -17,7 +17,6 @@ mod timeout;
 
 use azure_core::{error::ErrorKind, Error, Result};
 pub use azure_pipelines_credential::*;
-pub use chained_token_credential::*;
 pub use credentials::*;
 pub use managed_identity_credential::*;
 use std::borrow::Cow;