aarch64: add basic support for sme-f8f16 and sme-f8f32

aarch64: add basic support for sme-f8f16 and sme-f8f32

This patch adds support for the SME_F8F16 and SME_F8F32 features as architecture
options, along with related definitions. This support is required for subsequent
intrinsics to work.

gcc/
	* config/aarch64/aarch64.h:
	(TARGET_STREAMING_SME_F8F16, TARGET_STREAMING_SME_F8F32): Add defines.
	* config/aarch64/aarch64-c.cc:
	(__ARM_FEATURE_SME_F8F16, __ARM_FEATURE_SME_F8F32): Add defines.
	* config/aarch64/aarch64-option-extensions.def:
	(sme-f8f16, sme-f8f32): Add arch options in command line.
	* config/aarch64/aarch64-sve-builtins-functions.h:
	(sme_2mode_function_t): Pass unspec_for_mfp8 parameter through ctor.
	* config/aarch64/aarch64-sve-builtins-sme.def:
	(DEF_SME_FUNCTION_GS, DEF_SME_FUNCTION): Redefine based on
	DEF_SME_FUNCTION_GS_FPM.
	(DEF_SME_ZA_FUNCTION_GS, DEF_SME_ZA_FUNCTION): Redefine based on
	DEF_SME_ZA_FUNCTION_GS_FPM.
	(AARCH64_FL_SME_F8F16, AARCH64_FL_SME_F8F32): Add new
	REQUIRED_EXTENSIONS sections.
	* config/aarch64/aarch64-sve-builtins.cc:
	(TYPES_za_h_mf8): Add new types.
	(TYPES_za_s_mf8): Likewise.
	(sme_function_groups): Define using DEF_SME_FUNCTION_GS_FPM instead of
	DEF_SME_FUNCTION_GS.
	* doc/invoke.texi: (sme-f8f16, sme-f8f32): Add documentation of option.

gcc/testsuite/
	* gcc.target/aarch64/pragma_cpp_predefs_4.c: Add tests checking that
	sme-f8f16 and sme-f8f32 prefefs are off by default, and checks for
	feature dependencies.
	* lib/target-supports.exp: Add check_effective_target support for
	sme-f8f16 and sme-f8f32.