Fix for the 'DELETE generated files'

The option under 'Auto cleanup and sync' now uses p4 reconcile flags `-ed` (not the implied `-a` as these are the files you want to leave).

* Includes ground work for custom build args for Workspace names.  Takes `${parameter}` and replaces it with the value if defined or uses the tag (`parameter` in this case).

* Includes substitution for a space `' '` with `'_'` as per P4 behaviour.