ChatGPT Extended eftir TherioJunior

Adds the following to ChatGPT:
- Default Model Selector: no matter what you do on the site, new chats will be started with a through the extension selected model which is up to your choice. These are separated between the free GPT-3.5 Turbo and all the different paid GPT-4 versions. NOTE: This will not unlock those models, you'd still have to have OpenAI/ChatGPT Premium.

- Output Language: Choose and force ChatGPT to have the conversation with you in German, English or let it auto-detect the language for you. If you don't like it, you can have it set to nothing and let ChatGPT decide on its own (this is the default)

- Output/Conversation style: Have ChatGPT answer in a specific style. You can have it set to answer playfully, as an example.

- Output/Conversation tone: Have ChatGPT answer in a specific tone. You can, amongst other things, force the answers to be Journalistic, Creative, Precise, Technical or make ChatGPT explain it to your like you are 5 years old (ELI5)

Additionally, this adds a button to your chatbox which lets you make ChatGPT continue its answer and further expand what it was talking about by clicking this one button.