Add translation via ChatGPT

[magicus]

I have achieved very good, close to excellent, results in translating .srt files with the OpenAI ChatGPT API, using a simple python script and a just naively tweaked prompt.

It would be great if this functionality was integrated into Tero.

I'm sending the entire .srt file to ChatGPT and it usually handles it correctly, with the timings metadata and all, but sometimes it gets confused, so ideally it should get a text with some pre- and post-processing to make sure it really translates just the actual text lines. Having the entire context of the conversation is essential to the good performance, though.