Use regexp2 pkg for path validation

[jjngx]

Proposed changes

This PR fixes issue #797 and introduces following change:

• paths with regex expressions are verified using regexp2 package. The package implements Perl5 and .NET compatible regex engine

Testing:

Create VS:

apiVersion: k8s.nginx.org/v1
kind: VirtualServer
metadata:
  name: cafe
  namespace: default
spec:
  host: cafe.example.com
  upstreams:
  - name: tea
    service: tea-svc
    port: 80
  routes:
  - path: /tea
    action:
      pass: tea
  - path: /coffee
    route: default/coffee

Create VSR:

apiVersion: k8s.nginx.org/v1
kind: VirtualServerRoute
metadata:
  name: coffee
  namespace: default
spec:
  host: cafe.example.com
  upstreams:
  - name: latte
    service: latte-svc
    port: 80
  - name: espresso
    service: espresso-svc
    port: 80
  subroutes:
  - path: ~ ^/coffee/latte$ # it's works
    action:
      pass: latte
  - path: ~ ^/coffee/(?!.*\/latte)(?!.*\/americano)(.*) # it isn't working
    action:
      pass: espresso

Verify VSR is created and NIC is not reporting errors:

$ kubectl describe vsr coffee
Name:         coffee
Namespace:    default
Labels:       <none>
Annotations:  <none>
API Version:  k8s.nginx.org/v1
Kind:         VirtualServerRoute
Metadata:
  Creation Timestamp:  2023-10-03T16:34:18Z
  Generation:          1
  Resource Version:    291887
  UID:                 f57cd1fd-d8eb-4864-ba63-f2cb36578b1b
Spec:
  Host:  cafe.example.com
  Subroutes:
    Action:
      Pass:  latte
    Path:    ~ ^/coffee/latte$
    Action:
      Pass:  espresso
    Path:    ~ ^/coffee/(?!.*\/latte)(?!.*\/americano)(.*)
  Upstreams:
    Name:     latte
    Port:     80
    Service:  latte-svc
    Name:     espresso
    Port:     80
    Service:  espresso-svc
Status:
  Message:        Configuration for default/coffee was added or updated
  Reason:         AddedOrUpdated
  Referenced By:
  State:          Valid
Events:
  Type    Reason          Age   From                      Message
  ----    ------          ----  ----                      -------
  Normal  AddedOrUpdated  15s   nginx-ingress-controller  Configuration for default/coffee was added or updated

IC logs:

2023/10/03 16:34:19 [notice] 22#22: signal 29 (SIGIO) received
I1003 16:34:19.046547       1 event.go:298] Event(v1.ObjectReference{Kind:"VirtualServer", Namespace:"default", Name:"cafe", UID:"7f98147e-5127-4cb2-b4ec-5a11e178513c", APIVersion:"k8s.nginx.org/v1", ResourceVersion:"291855", FieldPath:""}): type: 'Normal' reason: 'AddedOrUpdated' Configuration for default/cafe was added or updated
I1003 16:34:19.046746       1 event.go:298] Event(v1.ObjectReference{Kind:"VirtualServerRoute", Namespace:"default", Name:"coffee", UID:"f57cd1fd-d8eb-4864-ba63-f2cb36578b1b", APIVersion:"k8s.nginx.org/v1", ResourceVersion:"291863", FieldPath:""}): type: 'Normal' reason: 'AddedOrUpdated' Configuration for default/coffee was added or updated
I1003 16:34:33.426801       1 leaderelection.go:260] successfully acquired lease nginx-ingress/nginx-ingress-leader-election

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

Merging #4465 (ab72f32) into main (c75d041) will not change coverage.
The diff coverage is 100.00%.

❗ Current head ab72f32 differs from pull request most recent head 408c919. Consider uploading reports for the commit 408c919 to get more accurate results

@@           Coverage Diff           @@
##             main    #4465   +/-   ##
=======================================
  Coverage   51.97%   51.97%           
=======================================
  Files          59       59           
  Lines       16956    16956           
=======================================
  Hits         8813     8813           
  Misses       7848     7848           
  Partials      295      295           

Files	Coverage Δ
internal/k8s/validation.go	93.56% <100.00%> (ø)
pkg/apis/configuration/validation/virtualserver.go	93.98% <100.00%> (ø)

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