Group texture packs under one picker section and add a Download from OrcaCloud shortcut

The texture picker lists every plugin pack as an indented, collapsible child of one
"Resource Texture" section, which now always renders so the new button is reachable even
before any pack is installed. A pack whose name carries a " by ..." suffix shows that part
on a smaller, dimmed second line, keeping the name line short.

The button switches to the Home tab and opens the OrcaCloud pane on the plugin hub filtered
to resource textures. A native open now also drives the homepage shell (nav highlight and the
cloud-mode layout), and the requested page is remembered so a sign-in re-seed keeps it.

Also fixes the PluginsDialog fuzzy-search script path, which pointed at a directory the file
is not in.

src/slic3r/GUI/WebViewDialog.cpp

@@ -556,6 +556,10 @@ void WebViewPanel::set_cloud_mode(bool on, const wxString& url)
             load_cloud_after_signout(url);
         }
         m_cloud_browser->Show();
+        // The homepage shell owns the nav highlight and the cloud-mode layout class. A native open
+        // (not the page's own GotoCloud) must ask it to switch; the page's SetCloudMode no-ops if it
+        // already did. OnDocumentLoaded re-applies this when the homepage was still loading.
+        RunScript("SetCloudMode(true)");
     } else if (m_cloud_browser) {
         // Closing keeps the pane alive with its session, so re-opening does not have to sign in
         // again (guide §10). Nothing is cleared here.