🧠 feat: Cohere support as Custom Endpoint

[danny-avila]

Summary

Introduces Cohere as a Custom Endpoint.

Uses an experimental new method of introducing custom endpoints, where the API does not need to conform to OpenAI spec.

The Cohere API is similar enough to allow this.

Closes #2318

Other Changes

• Optimized UnknownIcon handling
• Change default title prompt for OpenAI and Custom endpoints
• downgraded firebase package due to low rating vulnerabilities found in package (npm audit)
• Added typing where touched for improved intellisense (on VS Code)

Change Type

• New feature (non-breaking change which adds functionality)

Checklist

• My code adheres to this project's style guidelines
• I have performed a self-review of my own code
• I have commented in any complex areas of my code
• I have made pertinent documentation changes
• My changes do not introduce new warnings
• I have written tests demonstrating that my changes are effective or that my feature works
• Local unit tests pass with my changes
• Any changes dependent on mine have been merged and published in downstream modules.
• New documents have been locally validated with mkdocs

[Trapper4888]

Would be nice to support cohere's grounded RAG, but probably a bit to much custom code for librechat purpose.

[danny-avila]

Would be nice to support cohere's grounded RAG, but probably a bit to much custom code for librechat purpose.

not out of the question, just more involved than the initial chat support