SYCL RelWithDebInfo Build: Add -g1 (AMReX-Codes#3429)

Add `-g1` to RelWithDebInfo build with oneAPI SYCL compiler (i.e.,
IntelLLVM). This is because with `-g` the link step can be very slow and
the final executable can be order of magnitude bigger than that
generated with `-g1`.

This actually passes `-g -g1` to the compiler. The first flag `-g` comes
from CMake with the RelWithDebInfo build type. Here, the order of the
two flags matter, because the latter flag `-g1` overrides `-g`.

Tools/CMake/AMReXFlagsTargets.cmake

@@ -89,7 +89,7 @@ target_compile_options( Flags_CXX
  $<${_cxx_appleclang_rwdbg}:>
  $<${_cxx_appleclang_rel}:>
  $<${_cxx_intelllvm_dbg}:-O0 -Wall -Wextra -Wno-sign-compare -Wno-unused-parameter -Wno-unused-variable>
- $<${_cxx_intelllvm_rwdbg}:>
+ $<${_cxx_intelllvm_rwdbg}:-g1>
  $<${_cxx_intelllvm_rel}:>
  )