Add language-agnostic parsing of the backtick block with code snippet for `HuggingFaceRequestManage`

# Description
The [implementation](https://github.com/JetBrains-Research/TestSpark/blob/a5c0e7a6ce0daffb01fbf522109cc78706aad613/src/main/kotlin/org/jetbrains/research/testspark/tools/llm/generation/hf/HuggingFaceRequestManager.kt#L106C17-L106C40) of the method `HuggingFaceRequestManager.extractLLMGeneratedCode` has a hard-coded Java-specific parsing.

It should be re-implemented to either support Kotlin as well or, even better, be completely language-agnostic or language-parameterizable.

**Screenshots:**

Start with HuggingFaceRequestManager.kt at HuggingFaceRequestManager.extractLLMGeneratedCode, linked in the issue, and inspect the current Java-specific backtick-block parsing. Define whether the implementation should accept Kotlin too or expose language-independent or language-parameterized behavior; done means generated code snippets are parsed without relying only on Java syntax.

Written by the indexing model from the issue text.