feat(compat_oai): Refactor to match proposal.

[ssbushi]

TODOS:

• openAI.model support
• listModels support

Checklist (if applicable):

• [x] PR title is following https://www.conventionalcommits.org/en/v1.0.0/
• [x] Tested (manually, unit tested, etc.)
• [ ] Docs updated (updated docs or a docs bug required)

[pavelgj]

PR title: feat(js/plugins/compat_oai): ... please.