UPSTREAM PR #17924: Gigachat 3 tool parser and tests

[loci-dev]

Note

Source pull request: ggml-org/llama.cpp#17924

This PR adds a tool parser for parsing the function calls made by the Gigachat 3 models.
Models can generate only one function call using format:

{text}<|message_sep|>\n\nfunction call<|role_sep|>\n{json}
Where <|message_sep|>\n\n and <|role_sep|>\n are special tokens.

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