feat: Add new Vec type to frontend

noir_stdlib/src/collections/vec.nr

@@ -3,12 +3,22 @@
 // For a similar reason, no constructor for Vec is exposed yet since the type
 // is still in-progress.
 impl<T> Vec<T> {
+    /// Get an element from the vector at the given index.
+    /// Fails with a constraint error if the given index is
+    /// less than the length of the vector.
     #[builtin(vec_get)]
     fn get(_self: Self, _index: Field) -> T { }
 
+    /// Push a new element to the end of the vector, returning a
+    /// new vector with a length one greater than the
+    /// original unmodified vector.
     #[builtin(vec_push)]
     fn push(_self: Self, _elem: T) -> Self { }
 
+    /// Pop an element from the end of the given vector, returning
+    /// a new vector with a length of one less than the given vector,
+    /// as well as the popped element.
+    /// Fails with a constraint error if the given vector's length is zero.
     #[builtin(vec_pop)]
     fn pop(_self: Self) -> (Self, T) { }
 }