Rework and simplify Find click tracking

Description

• directs user to the expected page, always (this was an issue with previous release)
• works without server side URL validation which would otherwise has meant a request
  to Find and in some cases also a DDS lookup.
• does not break target="blank"
• only fires once for each link (until reloaded or if you go back)
• uses Fetch API for browsers that support it which won't cancel slow track requests, otherwise XHR
• using CTRL+CLICK opens in a new tab like expected and not in current tab.
• support for middleclick and cmd+click (mac)
• does not buffer requests to be sent at another time (which won't happen in cases where user leaves the site)
• clean links (href is the true link) and no onclick attribute.