add stub module for UA code

to be used to drive emulation for web clients

src/lib.rs

@@ -111,3 +111,5 @@ pub mod tcp;
 pub mod tls;
 
 pub mod http;
+
+pub mod ua;

src/ua/mod.rs

@@ -0,0 +1,23 @@
+//! User agent modules for Rama.
+//!
+//! TODO: Develop first version of this module
+
+#[derive(Debug)]
+#[non_exhaustive]
+/// User agent
+///
+/// TODO: develop first version of this struct
+pub struct UserAgent;
+
+impl UserAgent {
+    /// Create a new user agent
+    pub fn new() -> Self {
+        panic!("TODO:implement")
+    }
+}
+
+impl Default for UserAgent {
+    fn default() -> Self {
+        panic!("TODO:implement")
+    }
+}