Some hasJSActions, and general annotation-code, related cleanup in the viewer and API

- Add support for logical assignment operators, i.e. `&&=`, `||=`, and `??=`, with a Babel-plugin. Given that these required incrementing the ECMAScript version in the ESLint and Acorn configurations, and that platform/browser support is still fairly limited, always transpiling them seems appropriate for now.

 - Cache the `hasJSActions` promise in the API, similar to the existing `getAnnotations` caching. With this implemented, the lookup should now be cheap enough that it can be called unconditionally in the viewer.

 - Slightly improve cleanup of resources when destroying the `WorkerTransport`.

 - Remove the `annotationStorage`-property from the `PDFPageView` constructor, since it's not necessary and also brings it more inline with the `BaseViewer`.

 - Update the `BaseViewer.createAnnotationLayerBuilder` method to actaually agree with the `IPDFAnnotationLayerFactory` interface.[1]

 - Slightly tweak a couple of JSDoc comments.

---
[1] We probably ought to re-factor both the `IPDFTextLayerFactory` and `IPDFAnnotationLayerFactory` interfaces to take parameter objects instead, since especially the `IPDFAnnotationLayerFactory` one is becoming quite unwieldy. Given that that would likely be a breaking change for any custom viewer-components implementation, this probably requires careful deprecation.

web/annotation_layer_builder.js

@@ -137,8 +137,8 @@ class DefaultAnnotationLayerFactory {
    *   for annotation icons. Include trailing slash.
    * @param {boolean} renderInteractiveForms
    * @param {IL10n} l10n
-   * @param {boolean} enableScripting
-   * @param {Promise<boolean>} hasJSActionsPromise
+   * @param {boolean} [enableScripting]
+   * @param {Promise<boolean>} [hasJSActionsPromise]
    * @returns {AnnotationLayerBuilder}
    */
   createAnnotationLayerBuilder(