Enhance/pdf improvements (#6475)

Full-text search, highlights and assets alias support 
It also exposes a plugin API for highlight context menu   
    ```ts
    /**
       * Current it's only available for pdf viewer
       * @param label - displayed name of command
       * @param action - callback for the clickable item
       * @param opts - clearSelection: clear highlight selection when callback invoked
       */
      registerHighlightContextMenuItem: (
        label: string,
        action: SimpleCommandCallback,
        opts?: {
          clearSelection: boolean
        }
      ) => unknown
    ```

src/main/frontend/components/block.css

@@ -614,7 +614,7 @@ a.cloze-revealed {
 }
 
 .page-property-key {
-  @apply font-medium;
+  @apply font-medium whitespace-nowrap;
   color: var(--ls-secondary-text-color);
 }