[api-minor] Deprecate getGlobalEventBus and update the "viewer components" examples accordingly

To avoid outright breaking third-party usages of the "viewer components" the `getGlobalEventBus` functionality is left intact, but a deprecation message is printed if the function is invoked.

The various examples are updated to *explicitly* initialize an `EventBus` instance, and provide that when initializing the relevant viewer components.

web/interfaces.js

@@ -146,13 +146,15 @@ class IPDFTextLayerFactory {
    * @param {number} pageIndex
    * @param {PageViewport} viewport
    * @param {boolean} enhanceTextSelection
+   * @param {EventBus} eventBus
    * @returns {TextLayerBuilder}
    */
   createTextLayerBuilder(
     textLayerDiv,
     pageIndex,
     viewport,
-    enhanceTextSelection = false
+    enhanceTextSelection = false,
+    eventBus
   ) {}
 }