aarch64: add multi-vector floating-point adjust exponent intrinsics

aarch64: add multi-vector floating-point adjust exponent intrinsics

This patch adds the following intrinsics (all __arm_streaming only) along with
asm tests for them.

- FSCALE (multiple and single vector)
	- svfloat16x2_t svscale[_single_f16_x2](svfloat16x2_t zd, svint16_t zm)
	- svfloat32x2_t svscale[_single_f32_x2](svfloat32x2_t zd, svint32_t zm)
	- svfloat64x2_t svscale[_single_f64_x2](svfloat64x2_t zd, svint64_t zm)
	- svfloat16x4_t svscale[_single_f16_x4](svfloat16x4_t zd, svint16_t zm)
	- svfloat32x4_t svscale[_single_f32_x4](svfloat32x4_t zd, svint32_t zm)
	- svfloat64x4_t svscale[_single_f64_x4](svfloat64x4_t zd, svint64_t zm)

- FSCALE (multiple vectors)
	- svfloat16x2_t svscale[_f16_x2](svfloat16x2_t zd, svint16x2_t zm)
	- svfloat32x2_t svscale[_f32_x2](svfloat32x2_t zd, svint32x2_t zm)
	- svfloat64x2_t svscale[_f64_x2](svfloat64x2_t zd, svint64x2_t zm)
	- svfloat16x4_t svscale[_f16_x4](svfloat16x4_t zd, svint16x4_t zm)
	- svfloat32x4_t svscale[_f32_x4](svfloat32x4_t zd, svint32x4_t zm)
	- svfloat64x4_t svscale[_f64_x4](svfloat64x4_t zd, svint64x4_t zm)

Test structure is based on the urshl ones that have a similar structure in how
they treat arguments.

gcc/
	* config/aarch64/aarch64-sve-builtins-base.cc (svscale_impl): Added new
	class for dealing with all svscale functions (including sve)
	(svscale): updated FUNCTION macro call to make use of new class.
	* config/aarch64/aarch64-sve-builtins-sve2.def: (svscale):
	Added new DEF_SVE_FUNCTION_GS call to enable recognition of new variant.
	* config/aarch64/aarch64-sve2.md (@aarch64_sve_fscale<mode>): Added
	new define_insn. (@aarch64_sve_single_fscale<mode>): Likewise.
	* config/aarch64/iterators.md: (SVE_Fx24_NOBF): Added new iterator,
	similar to SVE_Fx24 but without brainfloat.
	(SVE_Fx24): Updated to make use of SVE_Fx24_NOBF.
	(SVSCALE_SINGLE_INTARG): Added new mode_attr.
	(SVSCALE_INTARG): Likewise.

gcc/testsuite/
	* gcc.target/aarch64/sme2/acle-asm/scale_f16_x2.c: : Added test file.
	* gcc.target/aarch64/sme2/acle-asm/scale_f16_x4.c: : Likewise.
	* gcc.target/aarch64/sme2/acle-asm/scale_f32_x2.c: : Added test file.
	* gcc.target/aarch64/sme2/acle-asm/scale_f32_x4.c: : Likewise.
	* gcc.target/aarch64/sme2/acle-asm/scale_f64_x2.c: : Added test file.
	* gcc.target/aarch64/sme2/acle-asm/scale_f64_x4.c: : Likewise.