Agent Config Changes: rename & update config_dirs & update exclude_logs

[aphralG]

Proposed changes

Rename config_dirs to allowed_directories in the agent config.
Change allowed_directories & exclude_logs to be an array of strings instead of a string in the agent config.
Renamed GetDefaultFeatures() to DefaultFeatures()
Change treat_warnings_as_errors default to false

Allowed Directories
Previous

config_dirs: "/etc/nginx:/usr/local/etc/nginx:/usr/share/nginx/modules:/var/run/nginx:/var/log/nginx"

Updated

allowed_directories: 
    - /etc/nginx
    - /usr/local/etc/nginx
    - /usr/share/nginx/modules
    - /var/run/nginx
    - /var/log/nginx

Exclude Logs
Previous

exclude_logs: "/var/log/nginx/error.log:/var/log/nginx/access.log"

Updated

exclude_logs: 
            - /var/log/nginx/error.log
            - /var/log/nginx/access.log

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING document
• I have run make install-tools and have attached any dependency changes to this pull request
• If applicable, I have added tests that prove my fix is effective or that my feature works
• If applicable, I have checked that any relevant tests pass after adding my changes
• If applicable, I have updated any relevant documentation (README.md)
• If applicable, I have tested my cross-platform changes on Ubuntu 22, Redhat 8, SUSE 15 and FreeBSD 13