Recaptcha not recognizing language change on first ngOnChanges call

[mikelseverson]

Background:
During initialization of the component, setupComponent calls registerCaptchaScript.

registerCaptchaScript adds the grecaptcha script tag for the language passed into the component via 'hl' binding.

If a grecaptcha script has already loaded, no script tag is added, the logic gets skipped. (see below)

    function (useGlobalDomain, render, onLoad, language) {
        var _this = this;
        if (this.grecaptchaScriptLoaded()) {
            // recaptcha script is alrseady loaded
            // just call the callback
            this.zone.run(function () {
                onLoad(window[_this.windowGrecaptcha]);
            });
            return;
        }
        // we need to patch the callback through global variable, otherwise callback is not accessible
        // note: https://github.com/Enngage/ngx-captcha/issues/2
        window[this.windowOnLoadCallbackProperty] = (/** @type {?} */ ((function () { return _this.zone.run(onLoad.bind(_this, window[_this.windowGrecaptcha])); })));
        // prepare script elem
        /** @type {?} */
        var scriptElem = document.createElement('script');
        scriptElem.innerHTML = '';
        scriptElem.src = this.getCaptchaScriptUrl(useGlobalDomain, render, language);
        scriptElem.async = true;
        scriptElem.defer = true;
        // add script to header
        document.getElementsByTagName('head')[0].appendChild(scriptElem);
    };

the issue:
first ngx-recaptcha2 component loads the grecaptcha in 'en' then is removed from dom
later a new ngx-recaptcha2 component initializes with 'fr' for a language
english gets reused on the new component, the hl value is ignored.
Now, if the second component now updates hl to 'es', ngx-recaptcha2 updates grecaptcha appropriately.

This seems to be caused by scriptService.cleanup not being called during the first hl value change.

        if (changes && changes.hl) {
            // cleanup scripts when language changes
            if (!changes.hl.firstChange && (changes.hl.currentValue !== changes.hl.previousValue)) {
                this.scriptService.cleanup();
            }
        }

Workaround:
reproducing scriptService.cleanup when destroying the first ngx-captcha seems to get the second component to initialize as expected.

  ngOnDestroy() {
    window.ngx_captcha_onload_callback = undefined;
    window.windowGrecaptcha = undefined;
  } 

Thanks for the building this out, it has been great to use!