fix: update getAzureIdentityAuthProvider and make tenant id and client id optional.

src/graph/auth.ts

@@ -32,14 +32,15 @@ export function getMsalAuthProvider(
   };
 }
 
-export function getAzureIdentityAuthProvider(
-  tenantId: string,
-  clientId: string,
-) {
-  const credential = new DefaultAzureCredential({
-    tenantId,
-    managedIdentityClientId: clientId,
-  });
+export function getAzureIdentityAuthProvider(tenantId?: string, clientId?: string) : GraphAuthProvider {
+  const credentialOptions = 
+    tenantId && clientId
+    ? { tenantId, managedIdentityClientId: clientId }
+    : undefined;
+
+  const credential = credentialOptions 
+    ? new DefaultAzureCredential(credentialOptions)
+    : new DefaultAzureCredential();
 
   const getBearerToken = getBearerTokenProvider(
     credential,