Fix Code Mode: Add message history customization

[Yiannis128]

Add the ability to customize how the history of the conversation is shown to the LLM when in Fix Code Mode. The following options are added:

• Show latest code state only: Will discard the previous patches from the LLM along with the initial code and ESBMC output. Instead, will only show the last ESBMC output.
• Show patches in reverse order: Will show the earlier patches last and the later ones first. The latest patch will be shown first.

The setting can be customized through the following fields:

message_history: normal/latest_only/reverse

[Yiannis128]

Need to write tests for it