Add tasks for all the new languages

Task/Stack/EchoLisp/stack.echolisp

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+; build stack [0 1 ... 9 (top)] from a list
+(list->stack (iota 10) 'my-stack)
+(stack-top 'my-stack) → 9
+(pop 'my-stack)  → 9
+(stack-top 'my-stack) → 8
+(push 'my-stack '🐸) ; any kind of lisp object in the stack
+(stack-empty? 'my-stack) → #f
+(stack->list 'my-stack) ; convert stack to list
+    → (0 1 2 3 4 5 6 7 8 🐸)
+(stack-swap 'my-stack) ; swaps two last items
+    → 8 ; new top
+(stack->list 'my-stack)
+     → (0 1 2 3 4 5 6 7 🐸 8) ; swapped
+(while (not (stack-empty? 'my-stack)) (pop 'my-stack)) ; pop until empty
+(stack-empty? 'my-stack)  → #t ; true
+
+(push 'my-stack 7)
+my-stack ; a stack is not a variable, nor a symbol - cannot be evaluated
+   ⛔ error: #|user| : unbound variable : my-stack
+(stack-top 'my-stack)  → 7