fix: fix assigning the readonly require on global object

[Fatme]

As the runtimes set the require as a readonly property to global object, it is not possible to assign to it when "strict" mode is used.
The following code throws an error in runtime TypeError: Attempted to assign to readonly property.

global.require = function () {
      throw Error();
}

Currently when tsc is used, the produced code is in strict mode and it does not work in runtime.
Currently when grunt is used, the produced code is not in strict mode.

The new behavior unifies the tsc and grunt commands and compiles the code in non strict mode.