Leadership calendar PDF

Still needs style tweaks to the PDF but figured I can tackle that next sprint.
Also this needs the following ENV vars set:

```
PDF_URL_RULE_1=/the-bureau/leadership-calendar/pdf/
PDF_RENDER_URL_1=DEMO-DOMAIN/the-bureau/leadership-calendar/print/
```
You don't have the `onerror` JS fallback in here, anyway, so the `noscript` isn't really necessary.

If PDFreactor handles SVGs fine, I think all we need is the SVG call. That would be much preferable to the PNG for sharpness when printing. If this is to be used on non-PDFreactor pages, though, that blows that approach.

If we go PNG only, I'll make a new PNG with appropriate resolution for print.