[Flang][FlangRT][Runtime] Add RT_OFFLOAD_API_GROUP_BEGIN to missing symbols on AMDGPU (#147612)
After the recent move to work queues, in certain cases when linking in
the fortran runtime built for offload on AMDGPU as required in certain
cases, we'll get missing symbols when linking. This PR tries to address
this issue by encompassing more of the library in
RT_OFFLOAD_API_GROUP_BEGIN, which has the affect of compiling these
functions for AMDGPU, resolving the missing symbols.
This PR should address the following issue:
https://github.com/llvm/llvm-project/issues/145888