* Add support for running UAT with an absolute path to the editor executable, and pass a full path when cooking or packaging.
* Fix path to the editor executable when launching a standalone editor instance for preview.
#jira UE-70785
#rb none
#ROBOMERGE-OWNER: ryan.gerleve
#ROBOMERGE-AUTHOR: ben.marsh
#ROBOMERGE-SOURCE: CL 5238647 in //UE4/Release-4.22/... via CL 5238651
#ROBOMERGE-BOT: ENGINE (Main -> Dev-Networking)
[CL 5255118 by ben marsh in Dev-Networking branch]
cd3b23b628