Add support for XingChen4

[shuxiaoqiong]

Overview

I opened this PR to support TeleAI's new model: xingchen4.
The XingChen model is a domestically developed LLM from China Telecom AI Technology Co., Ltd. (TeleAI), originally named "telechat," and is scheduled to be open-sourced soon.

Additional information

I have opened an issue and initiated a discussion regarding this, you can check it at #28153

So far, I have completed the following work:

• Registered the xingchen4 model architecture in the llama.cpp framework with parameter alignment.
• Implemented conversion and quantization of the model's safetensors weights to GGUF format.
• Added CPU backend inference support.
• Added GPU backend inference support, along with specific GGML operator implementations.
• Wrote and tested operator test cases.
• Conducted llama-perplexity and llama-bench evaluations.

Requirements

• I have read and agree with the contributing guidelines
• AI usage disclosure: YES
• AI helped me complete the steps of model file loading, conversion, quantization, and initial operator implementation, among others.

[ggml-gh-bot]

Hi @shuxiaoqiong, thanks for your contribution!

Per our contribution guidelines, the automated PR checker found the following issue(s) that need your attention:

• Multiple open PRs from a new contributor: We limit new contributors (those without a previously merged PR) to 1 open PR at a time. You currently have 2 open PRs.

• Multiple backend changes in one PR: When adding support for a new model or feature, focus on CPU support only in the initial PR. Add support for other backends like CUDA in follow-up PRs. If you have a good reason to modify multiple backends in one PR, please explain it.

• Large PR: Large changes require prior discussion (e.g. an issue or RFC) and maintainers may not be able to review this PR as-is. Consider splitting it into smaller, focused PRs.

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