Quality of life improvements for Mac / Linux that missed the initial 4.23 branch.
- UAT scripts now in project root
- SyncProject script moved out of NotForLicensees
- SyncProject script deals with writable build version files
- SyncProject script now treats -cl as optional argument (if omitted sync is to #head)
- Helper scripts for Building, opening the editor, and creating a p4config file.
#jira UE-37807
#rb na
[CL 7633933 by Andrew Grant in 4.23 branch]
