Switch to gpt-3.5 api

[TubsDK]

We need to move to the gpt-3.5 model

https://platform.openai.com/docs/api-reference/chat/create

This means added a few settings in site admin so that the user can choose to use gpt-3.5

It also means that the syntax must be slightly altereret into the chat format: https://platform.openai.com/docs/guides/chat/chat-vs-completions

[ {"role": "system", "content": "Du er en hjælpsom AI-asissisten, der skal hjælpe en studerende med at løse en opgave."}, {"role": "user", "content": '{text}'} ]

List of model endpoint compatibility: https://platform.openai.com/docs/models/model-endpoint-compatibility

IMPORTANT:

Chat completion API is still in beta. This change is breaking mod_smartlink. This cannot test without refactor OpenAI API handler behavior in mod_smartlink.

TODO:

• [x] Change AI model admin setting from text to drop down list that plugin is supported.
• [x] Manage API request. (Chat completion & Text completion required different parameters)
• [x] Manage API response. (Chat completion & Text completion response different data)
• [x] Remove unused settings. API URL is no longer needed, since AI models have different URL such as text-davinci-002 (text completion), text-davinci-003 (text completion), gpt-3.5-turbo (chat completion)
• [x] Implement test.

[sampraxis]

This should be close together with #1 when it has passed the test.