Add example usage for RestGetWithBackoff

Added a background script example for using RestGetWithBackoff.

Author: hanna-g-sn

Integration/RESTMessageV2/GET with backoff, telemetry, and simple pagination/example_background_usage.js

@@ -0,0 +1,11 @@
+// Background Script usage example for RestGetWithBackoff
+(function() {
+  var helper = new RestGetWithBackoff();
+  var data = helper.getAll({
+    endpoint: 'https://api.example.com/v1/things?limit=100',
+    headers: { 'Authorization': 'Bearer ${token}' },
+    maxRetries: 4,
+    baseDelayMs: 750
+  });
+  gs.info('Fetched ' + data.length + ' items total');
+})();