Add GPT Translation node count warning

[DraqueT]

• Add max nodes per model (based on this: https://platform.openai.com/docs/models/overview)
• Create an estimated token counter
• Every time a grammar section is added or removed, update estimate
• If the translation text goes unmodified for more than 1 second, update estimate
• estimate should be based on complete calculation of message. Do this in another thread so as not to tie up user experience.