[Internal] Add example for workspace unified authentication (#320)

## Changes

This PR adds an extremely simple example to show how to use workspace
unified authentication. This example is meant to be used by external CI
scripts that rely on examples to run integration tests.

Author: renaudhartert-db

examples/docs/src/main/java/com/databricks/example/UnifiedAuthWorkspace.java

@@ -0,0 +1,27 @@
+package com.databricks.example;
+
+import com.databricks.sdk.WorkspaceClient;
+import com.databricks.sdk.core.DatabricksConfig;
+import com.databricks.sdk.service.compute.ClusterDetails;
+import com.databricks.sdk.service.compute.ListClustersRequest;
+
+/**
+ Example for authenticating with Databricks Workspace through Databricks' Unified Authentication. Unified 
+ Authentication takes care of inspecting your environment to determine the best way to authenticate. 
+
+ <p>
+ For more details, please see <a href="https://docs.databricks.com/en/dev-tools/sdk-java.html#authenticate-the-databricks-sdk-for-java-with-your-databricks-account-or-workspace">Authenticate with Databricks SDK for Java</a>.
+ */
+public class UnifiedAuthWorkspace {
+    /**
+     Authenticate and retrieve the list of clusters from the workspace
+     */
+    public static void main(String[] args) {
+        DatabricksConfig config = new DatabricksConfig();
+
+        WorkspaceClient workspace = new WorkspaceClient(config);
+        for (ClusterDetails c : workspace.clusters().list(new ListClustersRequest())) {
+            System.out.println(c.getClusterName());
+        }
+    }
+}