Only send NGINX config context updates if there is a change

[dhurley]

Proposed changes

• Added checks to ensure that we only send NGINX config context updates if there is a change to the NGINX config
• Added checks to prevent NGINX config context updates from being sent while a config apply is in progress
• Added extra debug logging

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