Added Identity Token to TokenRefreshEventArgs (#367)

* Added Identity Token to TokenRefreshEventArgs

This change allows updating the identity token cached at the client with the latest identity token coming from token renewal

* Make Identity Token optional in TokenRefreshEventArgs to prevent breaking changes

Author: fmgracias

src/OidcClient/RefreshTokenDelegatingHandler.cs

@@ -180,7 +180,7 @@ private async Task<bool> RefreshTokensAsync(CancellationToken cancellationToken)
                             {
                                 try
                                 {
-                                    del(this, new TokenRefreshedEventArgs(response.AccessToken, response.RefreshToken, (int)response.ExpiresIn));
+                                    del(this, new TokenRefreshedEventArgs(response.AccessToken, response.RefreshToken, response.ExpiresIn, response.IdentityToken));
                                 }
                                 catch { }
                             }

src/OidcClient/TokenRefreshedEventArgs.cs

@@ -17,11 +17,12 @@ public class TokenRefreshedEventArgs : EventArgs
         /// <param name="accessToken">The access token.</param>
         /// <param name="refreshToken">The refresh token.</param>
         /// <param name="expiresIn">The expires in.</param>
-        public TokenRefreshedEventArgs(string accessToken, string refreshToken, int expiresIn)
+        public TokenRefreshedEventArgs(string accessToken, string refreshToken, int expiresIn, string identityToken = null)
         {
             AccessToken = accessToken;
             RefreshToken = refreshToken;
             ExpiresIn = expiresIn;
+            IdentityToken = identityToken;
         }
 
         /// <summary>
@@ -47,5 +48,13 @@ public TokenRefreshedEventArgs(string accessToken, string refreshToken, int expi
         /// The expires in.
         /// </value>
         public int ExpiresIn { get; }
+
+        /// <summary>
+        /// Gets the identity token.
+        /// </summary>
+        /// <value>
+        /// The identity token.
+        /// </value>
+        public string IdentityToken { get; }
     }
 }