Move basic auth policy validation to CRD

[pdabelf5]

Proposed changes

This change moved the basic auth policy validation to the CRD level, this ensures that the NIC process does not need to be involved in the Policy validation.

Tested with
valid full spec:

apiVersion: k8s.nginx.org/v1
kind: Policy
metadata:
  name: basic-auth-policy
spec:
  basicAuth:
    secret: abc123
    realm: "f f f"

missing required field:

apiVersion: k8s.nginx.org/v1
kind: Policy
metadata:
  name: basic-auth-policy
spec:
  basicAuth:
    realm: "a.b.c"

missing optional field:

apiVersion: k8s.nginx.org/v1
kind: Policy
metadata:
  name: basic-auth-policy
spec:
  basicAuth:
    secret: mysecret

invalid secret name:

apiVersion: k8s.nginx.org/v1
kind: Policy
metadata:
  name: basic-auth-policy
spec:
  basicAuth:
    secret: ABC123
    realm: "a.b.c"

invalid realm name:

apiVersion: k8s.nginx.org/v1
kind: Policy
metadata:
  name: basic-auth-policy
spec:
  basicAuth:
    secret: abc123
    realm: a.b.ci$

Checklist

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

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 52.70%. Comparing base (e03b216) to head (570d80d).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7257      +/-   ##
==========================================
- Coverage   52.72%   52.70%   -0.03%     
==========================================
  Files          89       89              
  Lines       20843    20833      -10     
==========================================
- Hits        10989    10979      -10     
+ Misses       9396     9395       -1     
- Partials      458      459       +1     

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