[CIR] Implement global array dtor support (#169070)
This implements handling to destroy global arrays that require
destruction. Unlike classic codegen, CIR emits the destructor loop into
a 'dtor' region associated with the global array variable. Later, during
LoweringPrepare, this code is moved into a helper function and a call to
__cxa_atexit arranges for it to be called during the shared object
shutdown.
