Please describe your feature request:

Add support for environment variables to specify custom paths for config files:

• SUBFINDER_CONFIG - Path to config.yaml file
• SUBFINDER_PROVIDER_CONFIG - Path to provider-config.yaml file

Describe the use case of this feature:

Docker environments: Currently users must mount config files to specific paths. With environment variables:

docker run -e SUBFINDER_CONFIG=/mounted/config.yaml -v /host/configs:/mounted projectdiscovery/subfinder

CI/CD pipelines: Config files are often in different locations or generated dynamically:

export SUBFINDER_CONFIG=/ci/generated/config.yaml
subfinder -d example.com

Multi-environment deployments: Easy switching between dev/staging/prod configs without changing commands.

This would improve usability in containerized and automated environments while maintaining backward compatibility. Similar functionality could benefit other ProjectDiscovery tools as well.