Experiment: Get line-based snippets for the input content
This MR implements a LineBasedCodeSnippets
iterator to get code snippets for a given file content based on a line number criterion.
Please, note this change doesn't affect the existing prompt logic and is provided for experimental purposes following #240.
Unit tests that represent the iterator logic - https://gitlab.com/gitlab-org/modelops/applied-ml/code-suggestions/ai-assist/-/blob/116604a4ec81d9c710c21af60a2776be3f90821d/tests/codesuggestions/prompts/snippets/test_lines.py Overall, the iterator returns a snippet after every n-th line.