* Legacy quants conversion schemes in convert_hf_to_gguf.py
This, notably in order to make smaller conversions to generate an iMatrix file.
`Q4_0`,`Q4_1` are here using embeddings, output, attn_k and attn_v in q5_0.
`Q5_0`,`Q5_1` are here using embeddings, output, attn_k and attn_v in q8_0.
Adapted from the following llama.cpp mainline PR : https://github.com/ggml-org/llama.cpp/pull/9022
Original author @chentyjpm
Also, 2 forgotten mentions of FTYPE IQ3_KL in llama.cpp file.
* forgotten IQ5_KS case mention
c7ecd4e23a