Help: Replace file:// URLs with launch:// URLs

LibWeb already thinks it knows how to handle `file://` URLs, so does not
call into the client to handle the URL scheme. Replacing these with
`launch://` means LibWeb will call into `handle_custom_scheme`, which
allows the Help app to process these requests.

Author: MacDue

Base/usr/share/man/man1/Applications/3DFileViewer.md

@@ -118,8 +118,11 @@ ErrorOr<void> MainWidget::initialize(GUI::Window& window)
 
     m_web_view = find_descendant_of_type_named<WebView::OutOfProcessWebView>("web_view");
     m_web_view->use_native_user_style_sheet();
-    m_web_view->handle_custom_scheme = [this](auto& url) {
-        if (url.scheme() == "file") {
+    m_web_view->handle_custom_scheme = [this](auto& custom_url) {
+        auto url = custom_url;
+        if (url.scheme() == "launch") {
+            // Treat "launch://" URLs as "file://" for use with Desktop::Launcher.
+            url.set_scheme("file"_string);
             auto path = LexicalPath { URL::percent_decode(url.serialize_path()) };
             if (!path.is_child_of(Manual::manual_base_path)) {
                 open_external(url);

Base/usr/share/man/man1/Applications/About.md

@@ -209,7 +209,7 @@ RecursionDecision MarkdownLinkage::visit(Markdown::Text::LinkNode const& link_no
             m_file_links.append({ file, ByteString(), StringCollector::from(*link_node.text) });
             return RecursionDecision::Recurse;
         }
-        if (url.scheme() == "file") {
+        if (url.scheme() == "file" || url.scheme() == "launch") {
             auto file_path = URL::percent_decode(url.serialize_path());
             if (file_path.contains("man"sv) && file_path.ends_with(".md"sv)) {
                 warnln("Inter-manpage link without the help:// scheme: {}\nPlease use help URLs of the form 'help://man/<section>/<subsection...>/<page>'", href);