[SYCL] Embed required fallback spv into final exeutable

[jinge90]

Currently, devicelib fallback spv must be distributed together with sycl runtime and sycl runtime must load required spv files into memory and link with user's device image if necessary, there are 2 problems about this behavior:

1. sycl runtime must use some hardly portable hack to get the full path of required spv files: https://github.com/intel/llvm/blob/sycl/sycl/source/detail/os_util.cpp#L109
2. users once complained that it was not acceptable for them to distribute a bunch of spv files together with sycl runtime, so we switched to AOT link for all device libraries except native bfloat16 libs

This PR is to address these 2 problems, we will embed the necessary fallback spv files into final executable as extra device images and sycl runtime will link these embedded device images with user's device image when necessary.

[jinge90]

We have decided to gradually remove the devicelib spv online link for most devicelib spv files and only keep bfloat16 devicelib for a short-term solution, so close this PR and create a new one for embedding required bfloat16 devicelib.