feat: update prompts for SAST FP detection flow

What does this merge request do and why?

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Update the prompts to fix the 404 errors we were getting for find_files, list_repository_tree and get_repository_file.
2. Add gitlab_blob_search tool for SAST FP detection component.
3. Update prompt to explicitly ask for a cross-function / cross-file dataflow analysis.

Notice that the input to the tool was incorrectly set as the GID instead of just the ID of the project thus we were getting 404 errors previously.

Merge request checklist

• Tests added for new functionality. If not, please raise an issue to follow up.
• Documentation added/updated, if needed.
• If this change requires executor implementation: verified that issues/MRs exist for both Go executor and Node executor or confirmed that changes are backward-compatible and don't break existing executor functionality.