[esimd] The plan of ESIMD in the future

[arthw]

1. Will ESIMD support new Intel GPUs in the future?
   Like B60/70 and the coming Intel GPU.

2. Will ESIMD support old Intel GPU (like Arc770) in new oneAPI release?
   I see Arc770 is removed from the comment of ESIMD exmple code: https://github.com/intel/llvm/tree/sycl/sycl/test-e2e/ESIMD.