Update to handle split_clients

[puneetsarna]

Proposed changes

split_clients is another map-like directive like geo that we need to account for while parsing an nginx conf as the body of the directive does not have valid nginx directives.

Checklist

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

• [x] I have read the CONTRIBUTING document
• [x] If applicable, I have added tests that prove my fix is effective or that my feature works
• [x] If applicable, I have checked that any relevant tests pass after adding my changes
• [x] I have updated any relevant documentation (README.md)

[puneetsarna]

@ornj @valyria257