The short of it: Even after gaining access to the "Enable Nozzle Temperature Control", I still wasn't able to used the "Auto Temperature" feature.
In my case, I was not able to get access to the "Enable Nozzle Temperature Control" option without first installing the printer settings plugin (Figure 1). Then you need to enable the "Show all Settings" option to get the "printer settings" tab to appear (Figure 2). However Even after going into the newly available "printer settings " tab and enabling "Enable Nozzle Temperature Control", the "Auto Temperature" feature was still un-enabled (Figure 3).
Plugins are now in the "Marketplace" not the now missing toolbox menu, which currently most things talking about Cura make reference too right now.
Windows 10 version 1809, Unlimaker Cura version 4.2.1
Figure 1.
Figure 2.
Figure 3.