[OpenMP] Detect SPMD compatible kernels and execute them as such

In the spirit of TRegions [0], this patch analyzes a kernel and tracks
if it can be executed in SPMD-mode. If so, we flip the arguments of
the __kmpc_target_init and deinit call to enable the mode. We also
update the `<kernel>_exec_mode` flag to indicate to the runtime we
changed the mode to SPMD.

The code analysis is done interprocedurally by extending the
AAKernelInfo abstract attribute to track SPMD compatibility as well.

[0] https://link.springer.com/chapter/10.1007/978-3-030-28596-8_11

Differential Revision: https://reviews.llvm.org/D102307