fix: Java cookbook recipes to compile with copilot-sdk-java 0.2.1-java.1

Fix compilation errors and documentation inaccuracies in Java cookbook
recipes against the actual SDK API:

- MultipleSessions: Replace non-existent destroy() with close()
- AccessibilityReport: Replace non-existent McpServerConfig class with
  Map<String, Object> (the actual type accepted by setMcpServers)
- error-handling.md: Replace non-existent session.addTool(),
  ToolDefinition.builder(), and ToolResultObject with actual SDK APIs
  (ToolDefinition.create(), SessionConfig.setTools(),
  CompletableFuture<Object> return type)

All 7 recipes now compile successfully with jbang build.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

cookbook/copilot-sdk/java/recipe/MultipleSessions.java

@@ -30,8 +30,7 @@ public class MultipleSessions {
             System.out.println("S3: " + s3.sendAndWait(new MessageOptions().setPrompt("Explain pattern matching")).get().getData().content());
 
             // Clean up
-            s1.destroy().get(); s2.destroy().get(); s3.destroy().get();
-            client.stop().get();
+            s1.close(); s2.close(); s3.close();
         }
     }
 }