Use ESLint to ensure that exports are sorted alphabetically

There's built-in ESLint rule, see `sort-imports`, to ensure that all `import`-statements are sorted alphabetically, since that often helps with readability.
Unfortunately there's no corresponding rule to sort `export`-statements alphabetically, however there's an ESLint plugin which does this; please see https://www.npmjs.com/package/eslint-plugin-sort-exports

The only downside here is that it's not automatically fixable, but the re-ordering is a one-time "cost" and the plugin will help maintain a *consistent* ordering of `export`-statements in the future.
*Note:* To reduce the possibility of introducing any errors here, the re-ordering was done by simply selecting the relevant lines and then using the built-in sort-functionality of my editor.

src/display/display_utils.js

@@ -642,21 +642,21 @@ class PDFDateString {
 }
 
 export {
-  PageViewport,
-  RenderingCancelledException,
   addLinkAttributes,
-  getFilenameFromUrl,
-  LinkTarget,
-  DEFAULT_LINK_REL,
   BaseCanvasFactory,
-  DOMCanvasFactory,
   BaseCMapReaderFactory,
+  DEFAULT_LINK_REL,
+  deprecated,
+  DOMCanvasFactory,
   DOMCMapReaderFactory,
   DOMSVGFactory,
-  StatTimer,
+  getFilenameFromUrl,
   isFetchSupported,
   isValidFetchUrl,
+  LinkTarget,
   loadScript,
-  deprecated,
+  PageViewport,
   PDFDateString,
+  RenderingCancelledException,
+  StatTimer,
 };