Implement Seed Parameter Support for OpenAI-Compatible API Endpoints

[GirinMan]

What does this PR do?

This PR introduces the capability to specify a seed for deterministic generation in the OpenAI-compatible API endpoints (/v1/chat/completion, etc.) of the LoRAX local LLM serving platform. This feature aligns LoRAX more closely with the official OpenAI API, which supports deterministic outputs by allowing a seed to be specified in requests.

Technical Details:

• The PR adds a seed parameter to the CompletionRequest and ChatCompletionRequest structures.
• It ensures that this seed is passed through to the CompatGenerateRequest during request processing, influencing the generation process to produce deterministic outputs.
• Relevant documentation has been updated to reflect this new capability and guide users on how to utilize it.

Dependencies:

• There are no new dependencies introduced by this change.

Fixes #373

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• Was this discussed/approved via a Github issue or the discord / slack channel? Please add a link
  to it if that's the case.
• Did you write any new necessary tests?

Who can review?

@tgaddair
cc. @soeque1

[tgaddair]

LGTM!