Fix: Rename _bookmarkWorkspaceCache to _workspaceBookmarksCache

Renames the internal cache variable `_bookmarkWorkspaceCache` to `_workspaceBookmarksCache` for consistency and clarity.  This change does not affect functionality.

src/browser/base/zen-components/ZenWorkspaces.mjs

@@ -782,7 +782,7 @@ var ZenWorkspaces = new (class extends ZenMultiWindowFeature {
 
       if(clearCache) {
         browser.ZenWorkspaces._workspaceCache = null;
-        browser.ZenWorkspaces._bookmarkWorkspaceCache = null;
+        browser.ZenWorkspaces._workspaceBookmarksCache = null;
       }
       let workspaces = await browser.ZenWorkspaces._workspaces();
       await browser.ZenWorkspaces.workspaceBookmarks();