[api-minor] Remove the xfaLayerFactory in the viewer

Please note that this functionality has never really mattered for the Firefox PDF Viewer, the GENERIC viewer, or even the "simpleviewer"/"singlepageviewer" component-examples. Hence, in practice this means that only the "pageviewer" component-example[1] have ever really utilized this.

Using factories to initialize various layers in the viewer, rather than simply invoking the relevant code directly, seems (at least to me) like a somewhat roundabout way of doing things.
Not only does this lead to more code, both to write and maintain, but since many of the layers have common parameters (e.g. an `AnnotationStorage`-instance) there's also some duplication.

Hence this patch, which removes the `xfaLayerFactory` and instead uses a lookup-function in the `PDFPageView`-class to access the external viewer-properties as necessary.
Note that this should even be an improvement for the "pageviewer" component-example, since most layers will now work by default rather than require manual configuration.

---
[1] In practice we generally suggest using the "simpleviewer", or "singlepageviewer", since it does *most* things out-of-the-box and given that a lot of functionality really require *a viewer* and not just a single page in order to work.

web/interfaces.js

@@ -18,7 +18,6 @@
 // eslint-disable-next-line max-len
 /** @typedef {import("../src/display/display_utils").PageViewport} PageViewport */
 /** @typedef {import("./ui_utils").RenderingStates} RenderingStates */
-/** @typedef {import("./xfa_layer_builder").XfaLayerBuilder} XfaLayerBuilder */
 
 /**
  * @interface
@@ -150,25 +149,6 @@ class IRenderableView {
   draw() {}
 }
 
-/**
- * @interface
- */
-class IPDFXfaLayerFactory {
-  /**
-   * @typedef {Object} CreateXfaLayerBuilderParameters
-   * @property {HTMLDivElement} pageDiv
-   * @property {PDFPageProxy} pdfPage
-   * @property {AnnotationStorage} [annotationStorage] - Storage for annotation
-   *   data in forms.
-   */
-
-  /**
-   * @param {CreateXfaLayerBuilderParameters}
-   * @returns {XfaLayerBuilder}
-   */
-  createXfaLayerBuilder({ pageDiv, pdfPage, annotationStorage = null }) {}
-}
-
 /**
  * @interface
  */
@@ -235,10 +215,4 @@ class IL10n {
   async translate(element) {}
 }
 
-export {
-  IDownloadManager,
-  IL10n,
-  IPDFLinkService,
-  IPDFXfaLayerFactory,
-  IRenderableView,
-};
+export { IDownloadManager, IL10n, IPDFLinkService, IRenderableView };