add: allow njs directives in all supported contexts

[valyria257]

Proposed changes

As of the 0.7.7 njs release, some js directives can now be specified in additional contexts. See https://nginx.org/en/docs/njs/changes.html#njs0.7.7 for all updated directives and respective allowed contexts.

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)