added support for chat.completion to return sse response

[raja-jamwal]

Describe your changes

• I was trying to use gpt4all with continue.dev but continue.dev expects SSE responses.
• Added changes to return SSE response.
• Tested with the publically available version of continue.dev and postman to validate the SSE response.

see this issue
#2174

Issue ticket number and link

Checklist before requesting a review

• I have performed a self-review of my code.
• If it is a core feature, I have added thorough tests.
• I have added thorough documentation for my code.
• I have tagged PR with relevant project labels. I acknowledge that a PR without labels may be dismissed.
• If this PR addresses a bug, I have provided both a screenshot/video of the original bug and the working solution.

Demo

Steps to Reproduce

• install continue.dev, set it up to use the existing local gpt4all server. Ask him something, it blanks out.
• Use this build to ask it something, and it'll respond.

Notes

[raja-jamwal]

@cebtenzzre Can I get a review on this?

[manyoso]

@cebtenzzre , please deal with this.