support Megrez-3B-Omni and fix mask padding

[MeouSker77]

Description

support Megrez-3B-Omni and fix mask padding

2. User API changes

use transformers 4.45

from ipex_llm.transformers import AutoModelForCausalLM
model = AutoModelForCausalLM.from_pretrained(
    path,
    trust_remote_code=True,
    load_in_low_bit='sym_int4',
    modules_to_not_convert=["vision"],
    attn_implementation="eager",
)
model = model.half().eval()
model = model.to('xpu')

...

response = model.chat(
    messages,
    sampling=True,     # necessary
    use_cache=True,    # important
    max_new_tokens=MAX_NEW_TOKENS,
    # temperature=0,
)

[rnwang04]

LGTM