Make Pirsch analytics integration optional

[runephilosof-abtion]

In order to build with a Pirsch key: docker compose build --build-arg PIRSCH_KEY="VEW6587Xat8LXjE7ejokwXUked6s7udc"

Parcel processes process.env.PIRSCH_KEY as a macro, so it will evaluate it at build time.

When supplying the PIRSCH_KEY, it generates the following index.html:

    <script>!function(){let t="VEW6587Xat8LXjE7ejokwXUked6s7udc";if(t){let e=document.createElement("script");e.setAttribute("src","https://api.pirsch.io/pirsch.js"),e.setAttribute("id","pirschjs"),e.setAttribute("defer",""),e.setAttribute("data-code",t)}}();</script><script>!function(){let t="VEW6587Xat8LXjE7ejokwXUked6s7udc";if(t){let e=document.createElement("script");e.setAttribute("src","https://api.pirsch.io/pirsch.js"),e.setAttribute("id","pirschjs"),e.setAttribute("defer",""),e.setAttribute("data-code",t)}}();</script>

Without supplying the PIRSCH_KEY, it generates:

    <script>!function(){let t=void 0;if(t){let e=document.createElement("script");e.setAttribute("src","https://api.pirsch.io/pirsch.js"),e.setAttribute("id","pirschjs"),e.setAttribute("defer",""),e.setAttribute("data-code",t)}}();</script>

Closes: https://github.com/webwhiz-ai/webwhiz/issues/220

[hrithikt]

@runephilosof-abtion we have removed pirsch analytics (0118c773d1d4e0526fd70138aecb103afd4278c3) completely from the widget.