[api-minor] Remove Outliner from the official API

As far as I can tell `Outliner` is only exposed in the API because we need to access it when running some of the reference-tests, but is otherwise not used.
Hence this seems like something that should be kept *internal* and thus only exposed in TESTING-builds.

src/pdf.js

@@ -80,6 +80,12 @@ const pdfjsVersion =
 const pdfjsBuild =
   typeof PDFJSDev !== "undefined" ? PDFJSDev.eval("BUNDLE_BUILD") : void 0;
 
+if (typeof PDFJSDev !== "undefined" && PDFJSDev.test("TESTING")) {
+  globalThis.pdfjsTestingUtils = {
+    Outliner,
+  };
+}
+
 export {
   AbortException,
   AnnotationEditorLayer,
@@ -109,7 +115,6 @@ export {
   noContextMenu,
   normalizeUnicode,
   OPS,
-  Outliner,
   PasswordResponses,
   PDFDataRangeTransport,
   PDFDateString,

test/driver.js

@@ -12,7 +12,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-/* globals pdfjsLib, pdfjsViewer */
+/* globals pdfjsLib, pdfjsTestingUtils, pdfjsViewer */
 
 const {
   AnnotationLayer,
@@ -20,12 +20,12 @@ const {
   DrawLayer,
   getDocument,
   GlobalWorkerOptions,
-  Outliner,
   PixelsPerInch,
   shadow,
   TextLayer,
   XfaLayer,
 } = pdfjsLib;
+const { Outliner } = pdfjsTestingUtils;
 const { GenericL10n, parseQueryString, SimpleLinkService } = pdfjsViewer;
 
 const WAITING_TIME = 100; // ms

test/unit/pdf_spec.js

@@ -61,7 +61,6 @@ import { AnnotationLayer } from "../../src/display/annotation_layer.js";
 import { ColorPicker } from "../../src/display/editor/color_picker.js";
 import { DrawLayer } from "../../src/display/draw_layer.js";
 import { GlobalWorkerOptions } from "../../src/display/worker_options.js";
-import { Outliner } from "../../src/display/editor/outliner.js";
 import { TextLayer } from "../../src/display/text_layer.js";
 import { XfaLayer } from "../../src/display/xfa_layer.js";
 
@@ -94,7 +93,6 @@ const expectedAPI = Object.freeze({
   noContextMenu,
   normalizeUnicode,
   OPS,
-  Outliner,
   PasswordResponses,
   PDFDataRangeTransport,
   PDFDateString,

web/pdfjs.js

@@ -42,7 +42,6 @@ const {
   noContextMenu,
   normalizeUnicode,
   OPS,
-  Outliner,
   PasswordResponses,
   PDFDataRangeTransport,
   PDFDateString,
@@ -89,7 +88,6 @@ export {
   noContextMenu,
   normalizeUnicode,
   OPS,
-  Outliner,
   PasswordResponses,
   PDFDataRangeTransport,
   PDFDateString,