ggml : Implementations for Q4_0_8_8 quantization based functions - RISC-V vector version

[xctan]

• This PR supersedes Implementations for Q4_0_8_8 quantization based functions - RISC-V vector version #9953
• The PR contains RISC-V Vector version of ggml_gemm_q4_0_8x8_q8_0 used for Q4_0_8_8 quantized models

I've tested Mistral 7B in qemu, and it just worked. I'm still choosing suitable 3B models for my dev board with only 4GB RAM (Banana Pi BPI-F3), so I can't give any performance evaluation as of now and any help is welcome! BTW Mistral 7B could run on BPI-F3 4GB with another 4GB swap memory enabled, but it was much slower than even qemu.

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[xctan]

Model: https://huggingface.co/CobraMamba/mamba-gpt-3b-v4
Compiler: GCC 13.2.0

model	size	params	backend	threads	test	t/s	speedup	commit
llama 3B Q4_0_8_8	1.84 GiB	3.43 B	CPU	8	pp512	1.82 ± 0.00	271%	78c78e2
llama 3B Q4_0_8_8	1.84 GiB	3.43 B	CPU	8	pp512	0.49 ± 0.00		66c2c93
llama 3B Q4_0_8_8	1.84 GiB	3.43 B	CPU	8	tg128	2.25 ± 0.10	350%	78c78e2
llama 3B Q4_0_8_8	1.84 GiB	3.43 B	CPU	8	tg128	0.50 ± 0.01		66c2c93