[api-minor] Add basic support for the SetOCGState action (issue 15372)

Note that this patch implements the `SetOCGState`-handling in `PDFLinkService`, rather than as a new method in `OptionalContentConfig`[1], since this action is nothing but a series of `setVisibility`-calls and that it seems quite uncommon in real-world PDF documents.

The new functionality also required some tweaks in the `PDFLayerViewer`, to ensure that the `layersView` in the sidebar is updated correctly when the optional-content visibility changes from "outside" of `PDFLayerViewer`.

---
[1] We can obviously move this code into `OptionalContentConfig` instead, if deemed necessary, but for an initial implementation I figured that doing it this way might be acceptable.

web/interfaces.js

@@ -110,6 +110,11 @@ class IPDFLinkService {
    */
   executeNamedAction(action) {}
 
+  /**
+   * @param {Object} action
+   */
+  executeSetOCGState(action) {}
+
   /**
    * @param {number} pageNum - page number.
    * @param {Object} pageRef - reference to the page.