modernize samples code

[paroj]

the samples code could be improved by

• using range based for loops
• using RGN_DEFAULT instead of DEFAULT_RESOURCE_GROUP_NAME
• using HBU_CPU_TO_GPU instead of HBU_DYNAMIC_WRITE_ONLY
• using std::vector or std::unique_ptr instead of raw new & delete

[paroj]

@Joilnen FYI