[AArch64] Add intrinsics for multi-vector to ZA array vector accumulators (#88266)

According to the specification in
https://github.com/ARM-software/acle/pull/309 this adds the intrinsics

void_svadd_za16_vg1x2_f16(uint32_t slice, svfloat16x2_t zn)
__arm_streaming __arm_inout("za");
void_svadd_za16_vg1x4_f16(uint32_t slice, svfloat16x4_t zn)
__arm_streaming __arm_inout("za");
void_svsub_za16_vg1x2_f16(uint32_t slice, svfloat16x2_t zn)
__arm_streaming __arm_inout("za");
void_svsub_za16_vg1x4_f16(uint32_t slice, svfloat16x4_t zn)
__arm_streaming __arm_inout("za");

as well as the corresponding `bf16` variants.