[SYCL] Implement updates to the root group extension

[lbushi25]

Implement the updates made to the root group extension as described here: #21838

[lbushi25]

@koparasy I see that my PR is causing the test https://github.com/intel/llvm/blob/1a6dd8c780643a46f6c9242516b845f2219b426c/sycl/test/include_deps/header_reach.cpp to fail. I have taken a look and I'm not sure why the fail is happening. My PR does not add any new #include lines. Is this an issue on my end or with the header_reach_check.py script?

[lbushi25]

@koparasy I see that my PR is causing the test https://github.com/intel/llvm/blob/1a6dd8c780643a46f6c9242516b845f2219b426c/sycl/test/include_deps/header_reach.cpp to fail. I have taken a look and I'm not sure why the fail is happening. My PR does not add any new #include lines. Is this an issue on my end or with the header_reach_check.py script?

For the logs, see: https://github.com/intel/llvm/actions/runs/28829463684/job/85499991921?pr=22552

[koparasy]

@koparasy I see that my PR is causing the test https://github.com/intel/llvm/blob/1a6dd8c780643a46f6c9242516b845f2219b426c/sycl/test/include_deps/header_reach.cpp to fail. I have taken a look and I'm not sure why the fail is happening. My PR does not add any new #include lines. Is this an issue on my end or with the header_reach_check.py script?

For the logs, see: https://github.com/intel/llvm/actions/runs/28829463684/job/85499991921?pr=22552

You are having compilation errors sycl/include/sycl/kernel.hpp when a TU includes this file. Basically, the header file is not including everything it needs to be self contained.