feat: Implement function parameters and return values

examples/functions_with_params.fem

@@ -0,0 +1,12 @@
+Femboy add_numbers(a, b) Femboycore
+    Femme a + b
+Periodt
+
+result is add_numbers(10, 5)
+UwU Boy result
+
+Femboy greet(name) Femboycore
+    UwU Boy "Hello, " + name
+Periodt
+
+greet("World")