add DG1 helper

[jeffhammond]

Helpful tip from Phil:

Add the following to the Gen12LP banner...

#
# Compile-time requirement - DG1-specific
#
export IGC_EnableDPEmulation=1
#
# Runtime requirement - DG1-specific
#
export OverrideDefaultFP64Settings=1
export SYCL_DEVICE_WHITE_LIST=""