Create new stage for Symbian^3 update for Qt

Add new stage for new Symbian^3 update. There is couple of important things when doing this:

• EPOCROOT must start with drive letter (Pre-target MOC command is launched using EPOCROOT and SBS using cygwin cannot resolve paths starting with slash in same way as Windows does)
• There is now two Symbian^3 stages using the same agents. Disk space is not enough for parallel environments so the EPOCROOT must be same for both and environment must be re-installed for every test compilation
• IncrediBuild configuration is not compatible with new Raptor (2.15.x) - either disable it for Qt or investigate the problem and fix configuration if possible