Refactor evaluator class to interpreter class visitor-pattern branch

[gravataLonga]

There are some edges cases when function identifier isn't declare, e.g.:

var a = {"fn": add};

function add() {

};

This will give error, because add identifier isn't yet declare, we need more study on this.

[gravataLonga]

We are now implement this with semantic analyzer.
https://github.com/gravataLonga/ninja/tree/main/semantic.

[gravataLonga]

Major refactor is happening in branch visitor-pattern. We are change way we interpreter values for a visitor pattern, this way we can handle edges cases like this one. Also it will prevent leaks of variables for example

var a ="global";
function () {
   function showA()  { puts(a); }
   
   showA();
   var a = "local";
  showA();
}();