MLECO-6339: Investigate and improve the stop word seeking logic
- improved test time for cpp path for LLM with faster checking for stop word
- utility function added inside cpp layer for checking for stop word
- Existing tests passing for all paths
- stopWord container now uses std::vector instead of std::list
- SetupTestConfig refactored to GetTestConfigStopWords
Change-Id: I57afce2bbe9c83588ec6442332879e61924a9352 Signed-off-by: Olawole Abayomi-Owodunni olawole.abayomi-owodunni@arm.com