feat(backend): enhance rate limiting with dynamic model identifier

[nkanf-dev]

This pull request includes several changes to improve the rate-limiting functionality and logging in the backend. The most important changes include updating the identifier parameter to be a function, adding logging capabilities, and ensuring proper initialization of token bucket values.

Rate-limiting enhancements:

• backend/src/api/v1/completions.ts: Modified the identifier parameter in the rate limit configuration to be a function that extracts the model from the request body.
• backend/src/plugins/rateLimitPlugin.ts: Updated the identifier parameter to be a function that can process the request body, added error handling for the identifier function, and included debug logging for rate limit checks.

Logging improvements:

• backend/src/plugins/rateLimitPlugin.ts: Imported consola for logging and created a logger instance with a specific tag for the rate limit plugin.

Token bucket initialization:

• backend/src/utils/tokenBucket.ts: Added logic to initialize token and last refill values in Redis if they do not exist, ensuring the token bucket is correctly set up.

[nkanf-dev]

This pull request introduces a new rate-limiting feature to the backend API, along with several related enhancements. The changes include adding new rate limit configurations, updating existing API routes to utilize these configurations, and improving the rate limit plugin.

New rate-limiting feature:

• backend/src/api/admin/index.ts: Imported adminRateLimits and added it to the routes to handle rate limit configurations. [1] [2]
• backend/src/api/admin/rateLimits.ts: Created new API endpoints to get, set, and delete rate limit configurations.

Improvements to the rate limit plugin:

• backend/src/plugins/rateLimitPlugin.ts: Updated the rate limit plugin to support dynamic rate limit configurations and added logging.

Utility functions for rate limit configurations:

• backend/src/utils/rateLimitConfig.ts: Added functions to get, set, and delete rate limit configurations, along with a default configuration and logging.