Fortran: Add transfer_between_remotes [PR107635]

Add the last missing coarray data manipulation routine using remote
accessors.

gcc/fortran/ChangeLog:

	PR fortran/107635

	* coarray.cc (rewrite_caf_send): Rewrite to
	transfer_between_remotes when both sides of the assignment have
	a coarray.
	(coindexed_code_callback): Prevent duplicate rewrite.
	* gfortran.texi: Add documentation for transfer_between_remotes.
	* intrinsic.cc (add_subroutines): Add intrinsic symbol for
	caf_sendget to allow easy rewrite to transfer_between_remotes.
	* trans-decl.cc (gfc_build_builtin_function_decls): Add
	prototype for transfer_between_remotes.
	* trans-intrinsic.cc (conv_caf_vector_subscript_elem): Mark as
	deprecated.
	(conv_caf_vector_subscript): Same.
	(compute_component_offset): Same.
	(conv_expr_ref_to_caf_ref): Same.
	(conv_stat_and_team): Extract stat and team from expr.
	(gfc_conv_intrinsic_caf_get): Use conv_stat_and_team.
	(conv_caf_send_to_remote): Same.
	(has_ref_after_cafref): Mark as deprecated.
	(conv_caf_sendget): Translate to transfer_between_remotes.
	* trans.h: Add prototype for transfer_between_remotes.

libgfortran/ChangeLog:

	* caf/libcaf.h: Add prototype for transfer_between_remotes.
	* caf/single.c: Implement transfer_between_remotes.

gcc/testsuite/ChangeLog:

	* gfortran.dg/coarray_lib_comm_1.f90: Fix up scan_trees.