Fetch binary CMap data in the worker-thread, when useWorkerFetch is set

This patch uses the new option added in PR 12726 to *also* allow fetching binary CMap data directly in the worker-thread in browsers.
Given that these changes remove the need to transfer data between threads for the default (browser) use-case, we can also revert the changes in PR 11118 since that simplifies the overall implementation.

test/driver.js

@@ -19,7 +19,7 @@
 
 const WAITING_TIME = 100; // ms
 const PDF_TO_CSS_UNITS = 96.0 / 72.0;
-const CMAP_URL = "../external/bcmaps/";
+const CMAP_URL = "/build/generic/web/cmaps/";
 const CMAP_PACKED = true;
 const STANDARD_FONT_DATA_URL = "/build/generic/web/standard_fonts/";
 const IMAGE_RESOURCES_PATH = "/web/images/";

test/test_manifest.json

@@ -4046,6 +4046,15 @@
       "lastPage": 1,
       "type": "eq"
     },
+    {  "id": "mao-main_thread_fetch",
+       "file": "pdfs/mao.pdf",
+       "md5": "797093d67c4d4d4231ac6e1fb66bf6c3",
+       "rounds": 1,
+       "link": true,
+       "lastPage": 1,
+       "type": "eq",
+       "useWorkerFetch": false
+    },
     {  "id": "mao-text",
        "file": "pdfs/mao.pdf",
        "md5": "797093d67c4d4d4231ac6e1fb66bf6c3",