Add tasks for all the new languages

Task/Constrained-genericity/Morfa/constrained-genericity-1.morfa

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+import morfa.type.traits;
+
+template < T >
+alias IsEdible = HasMember< T, "eat" >;
+
+template < T >
+if (IsEdible< T >)
+struct FoodBox
+{
+    var food: T[];
+}
+
+struct Carrot
+{
+    func eat(): void {}
+}
+
+struct Car {}
+
+func main(): void
+{
+    var carrotBox: FoodBox< Carrot >;   // OK
+    carrotBox.food ~= Carrot();        // Adds a carrot
+
+    // var carBox: FoodBox< Car >;      // Not allowed
+    static assert( not trait(compiles, func() { var carBox: FoodBox< Car >; } ));
+}

Task/Constrained-genericity/Morfa/constrained-genericity-2.morfa

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+interface IEdible
+{
+    public func eat(): void;
+}
+
+template < T >
+if (IsDerivedOf< T, IEdible >)
+struct FoodBox
+{
+    var food: T[];
+}
+
+class Carrot: IEdible
+{
+    public override func eat(): void {}
+}
+
+class Car {}
+
+func main(): void
+{
+    var carrotBox: FoodBox< Carrot >;   // OK
+
+    // var carBox: FoodBox< Car >;      // Not allowed
+    static assert( not trait(compiles, func() { var carBox: FoodBox< Car >; } ));
+}