NLB-7404: Add custom directives for NGINXaaS usecase

[Naveen-Gopu-F5]

Proposed changes

Usecase :

NGINXaaS for Azure need 2 new custom directives (pseudo directives) which we will be using for the VMSS backend support feature. Since these directives are not part of nginx we want to add parsing, analyzing rules for these 2 new directives.

We will be using those in our control plane part and not in dataplane where actual nginx configuration applies and uses them.

upstream my-upstream {
        state /tmp/my-upstream.state;
        zone my-upstream 64k;
        nginxaas-scaling-group <AZURE_RESOURCE_ID>;
		nginxaas-scaling-group-opts max_conns=0 max_fails=1 fail_timeout=10s;
}

nginxaas-scaling-group : This directive specifies the resource_id of the user's VMSS (Example : /subscriptions//resourceGroups//providers/Microsoft.Compute/virtualMachineScaleSets/)

nginxaas-scaling-group : This directive specifies some of the configuration details.

Describe the use case and detail of the change. If this PR addresses an issue on GitHub, make sure to include a link to that issue using one of the supported keywords here in this description (not in the title of the PR).

Checklist

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

• I have read the CONTRIBUTING document
• 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
• I have updated any relevant documentation (README.md)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.51%. Comparing base (eaaaa89) to head (33aa712).
⚠️ Report is 32 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #170      +/-   ##
==========================================
+ Coverage   76.63%   78.51%   +1.87%     
==========================================
  Files          27       32       +5     
  Lines        1164     1182      +18     
==========================================
+ Hits          892      928      +36     
+ Misses        216      201      -15     
+ Partials       56       53       -3     

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[ryepup]

I don't think nginx-go-crossplane is a good place for this; these are NGINXaaS specific directives and we don't want to affect other users of nginx-go-crossplane.

Can we move this one file into the NGINXaaS repo, and add it to our crossplane configuration? All the C, JSON, plumbing aren't really needed. We know the shape of the directives we want to add and we can specify that directly.

[Naveen-Gopu-F5]

closing this PR, since we will be making changes in our NGINXaaS repo.