FEAT: Add repeated token attack converter

[jl8771]

Description

Add a converter based on this paper that repeats a specified token a specified number of times in one of four modes:

1. Prepend repeated tokens to prompt
2. Append repeated tokens to prompt
3. Add repeated tokens after first sentence of prompt (after first '.' '!' or '?' character). Remainder of prompt appended after repeated tokens.
   • default option, if no punctuation will prepend repeated tokens to prompt.
4. Ignore prompt, repeat tokens only

Tests and Documentation

Added tests to test_prompt_converter.py, one for each insert mode, repeats 'test' three times.