Chore: Shift environment variables to parameter store

[flamingquaks]

Currently, Lambda functions leverage environment variables for many of the configurations. Because majority of the logic is handled in genai_core, it somewhat hides what environment variables would need to be attached to a lambda.

If more functions are introduced, this requires each of these functions to have environment variables attached for code that isn't living in the main handler. Additionally, if genai_core logic is changed and requires new/different variables, the lambda that is calling the genai_core code would have to be updated or would break.

Proposal Shifting to parameter store for these values allows genai_core packages to retrieve the configurations without requiring the lambda function to have environment variables maintained. Lambdas would simply need to have access to the configuration.