feature/add impl (#6)

* format code

* with object gen and args

* add implementation

* add rust generator

* reset generated code

* add basic output

* reset output

* add object

* add format function

* with opts

* fix vec

* add context to unwrap

* fix arguments

* with function body

* first complete generation: Still missing Vec<Obj>

* run full alpine

* add roadmap item

crates/dagger-codegen/src/utility.rs

@@ -0,0 +1,18 @@
+pub trait OptionExt<'t, T: 't> {
+    fn pipe<U, F>(&'t self, f: F) -> Option<U>
+    where
+        F: FnOnce(&'t T) -> U;
+}
+
+impl<'t, T: 't> OptionExt<'t, T> for Option<T> {
+    #[inline]
+    fn pipe<U, F>(&'t self, f: F) -> Option<U>
+    where
+        F: FnOnce(&'t T) -> U,
+    {
+        match *self {
+            Some(ref x) => Some(f(x)),
+            None => None,
+        }
+    }
+}