Fortran: Fix [Coarray] ICE in conv_caf_send, at fortran/trans-intrinsic.c:1950 [PR84246]

Fix ICE caused by converted expression already being pointer by checking
for its type.  Lift rewrite to caf_send completely into resolve and
prevent more temporary arrays.

	PR fortran/84246

gcc/fortran/ChangeLog:

	* resolve.cc (caf_possible_reallocate): Detect arrays that may
	be reallocated by caf_send.
	(resolve_ordinary_assign): More reliably detect assignments
	where a rewrite to caf_send is needed.
	* trans-expr.cc (gfc_trans_assignment_1): Remove rewrite to
	caf_send, because this is done by resolve now.
	* trans-intrinsic.cc (conv_caf_send): Prevent unneeded temporary
	arrays.

libgfortran/ChangeLog:

	* caf/single.c (send_by_ref): Created array's lbound is now 1
	and the offset set correctly.

gcc/testsuite/ChangeLog:

	* gfortran.dg/coarray_allocate_7.f08: Adapt to array being
	allocate by caf_send.