Add disable rate limiter option and environment variable support

[lm-ranjeet-gavali]

1. Add Disable Rate Limiter Option:

• Introduced a NoopRateLimiter implementation.
• When this is used, no rate limiting is applied — all requests are allowed through unconditionally.
• Useful for development, testing, or environments where rate limiting is not needed.

2. Support for Environment Variables:

• If the rate limiter is enabled and explicit values are not set, the configuration will now:

  • First look for environment variables for request and span limits.
  • If env variables are also absent, it will fall back to default hardcoded values.

• This allows easier runtime customization without code changes.

3. Added "" string to the ConvertToLMLogInput methods , to resolve errors.

[khyatigandhi0612]

Looks ok to me