feat: Support GigaChat LLM from Langchain

[Rai220]

Adds support of gigachat LLM, that already supported in langchain: https://python.langchain.com/docs/integrations/chat/gigachat/

[codspeed-hq]

CodSpeed Performance Report

Merging #5453 will degrade performances by 94.36%

_{Comparing Rai220:main (10821ea) with main (3454ede)}

Summary

⚡ 1 improvements
❌ 1 regressions
✅ 13 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	main	Rai220:main	Change
⚡	test_get_and_cache_all_types_dict	1.5 ms	1.1 ms	+39.97%
❌	test_successful_run_with_output_type_debug	268.1 ms	4,752.6 ms	-94.36%