Validate ingress path fields

[rikatz]

What this PR does / why we need it:

Adds validation on "path" fields in Ingress objects

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• CVE Report (Scanner found CVE and adding report)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation only

Which issue/s this PR fixes

How Has This Been Tested?

Added additional unit and e2e tests

Does my pull request need a release note?

Validate the path field on ingress objects. Now Ingresses without regex annotation will just accept a small set of characters as path, and with regex annotation enabled will accept this small set of characters + characters required for regex to work

[k8s-ci-robot]

@rikatz: This issue is currently awaiting triage.

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[tao12345666333]

LGTM

[tao12345666333]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: rikatz, tao12345666333

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[haisum]

@rikatz This seems to have broken our ingress resources.

This was working before this change:

spec:
  ingressClassName: internal-ingress
  rules:
  - host: foo.com
    http:
      paths:
      - backend:
          service:
            name: foo
            port:
              number: 8080
        path: /foo(/|$)(.*)
        pathType: Prefix

What would be a 'valid' path in above after this change?

[matthewdevenny]

To add to this... Would it not be better to use url.ParseRequestURI to validate the non-regex path? I think this change currently doesn't support all valid URI paths.