AK: Add LexicalPath::is_root()

Author: https://github.com/stasoid
Commit: a423493dd8
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/2188
Reviewed-by: https://github.com/ADKaster ✅

AK/LexicalPath.h

@@ -28,6 +28,8 @@ public:
 
     static bool is_absolute_path(StringView path);
     bool is_absolute() const { return is_absolute_path(m_string); }
+    bool is_root() const;
+
     ByteString const& string() const { return m_string; }
 
     StringView dirname() const { return m_dirname; }