arm: [MVE intrinsics] Add support for contiguous loads and stores

arm: [MVE intrinsics] Add support for contiguous loads and stores

This patch adds base support for load/store intrinsics to the
framework, starting with loads and stores for contiguous memory
elements, without extension nor truncation.

Compared to the aarch64/SVE implementation, there's no support for
gather/scatter loads/stores yet.  This will be added later as needed.

2023-11-16  Christophe Lyon  <christophe.lyon@linaro.org>

	gcc/
	* config/arm/arm-mve-builtins-functions.h (multi_vector_function)
	(full_width_access): New classes.
	* config/arm/arm-mve-builtins.cc
	(find_type_suffix_for_scalar_type, infer_pointer_type)
	(require_pointer_type, get_contiguous_base, add_mem_operand)
	(add_fixed_operand, use_contiguous_load_insn)
	(use_contiguous_store_insn): New.
	* config/arm/arm-mve-builtins.h (memory_vector_mode)
	(infer_pointer_type, require_pointer_type, get_contiguous_base)
	(add_mem_operand)
	(add_fixed_operand, use_contiguous_load_insn)
	(use_contiguous_store_insn): New.