Improve utilities for gwctl describe and add more info to gateway descriptions

[gauravkghildiyal]

What this PR does / why we need it:

• Add helpers to print gwctl describe views and Tables
• Add more information when describing Gateways (like attached routes)
• Discover events associated with Gateways and output them when describing Gateways.

Example:

❯ gwctl describe gateways
Name: demo-gateway-1
Namespace: default
Labels: null
Annotations:
  kubectl.kubernetes.io/last-applied-configuration: |
    {"apiVersion":"gateway.networking.k8s.io/v1beta1","kind":"Gateway","metadata":{"annotations":{},"name":"demo-gateway-1","namespace":"default"},"spec":{"gatewayClassName":"foo-com-external-gateway-class","listeners":[{"name":"http","port":80,"protocol":"HTTP"}]}}
APIVersion: gateway.networking.k8s.io/v1
Kind: Gateway
Metadata:
  creationTimestamp: "2024-04-03T04:27:12Z"
  generation: 1
  managedFields:
  - apiVersion: gateway.networking.k8s.io/v1beta1
    fieldsType: FieldsV1
    fieldsV1:
      f:metadata:
        f:annotations:
          .: {}
          f:kubectl.kubernetes.io/last-applied-configuration: {}
      f:spec:
        .: {}
        f:gatewayClassName: {}
        f:listeners:
          .: {}
          k:{"name":"http"}:
            .: {}
            f:allowedRoutes:
              .: {}
              f:namespaces:
                .: {}
                f:from: {}
            f:name: {}
            f:port: {}
            f:protocol: {}
    manager: kubectl-client-side-apply
    operation: Update
    time: "2024-04-03T04:27:12Z"
  resourceVersion: "2531077"
  uid: 034c4490-6b0d-41f0-8d90-3948dbae4b6c
Spec:
  gatewayClassName: foo-com-external-gateway-class
  listeners:
  - allowedRoutes:
      namespaces:
        from: Same
    name: http
    port: 80
    protocol: HTTP
Status:
  conditions:
  - lastTransitionTime: "1970-01-01T00:00:00Z"
    message: Waiting for controller
    reason: Pending
    status: Unknown
    type: Accepted
  - lastTransitionTime: "1970-01-01T00:00:00Z"
    message: Waiting for controller
    reason: Pending
    status: Unknown
    type: Programmed
AttachedRoutes:
  Kind       Name
  ----       ----
  HTTPRoute  default/demo-httproute-1
  HTTPRoute  default/demo-httproute-2
  HTTPRoute  default/demo-httproute-3
  HTTPRoute  ns2/demo-httproute-4
DirectlyAttachedPolicies:
  Type                       Name
  ----                       ----
  HealthCheckPolicy.foo.com  default/demo-health-check-1
  RetryOnPolicy.foo.com      default/demo-retry-policy-1
EffectivePolicies:
  HealthCheckPolicy.foo.com:
    sampleParentField:
      sampleField: hello
  RetryOnPolicy.foo.com:
    sampleParentField:
      sampleField: namaste
  TimeoutPolicy.bar.com:
    timeout1: parent
    timeout2: child
    timeout3: parent
    timeout4: child
Events:
  Type     Reason  Age  From                   Message
  ----     ------  ---  ----                   -------
  Warning  SYNC    12h  my-gateway-controller  Some message here

Notes for reviewer: Reviewing individual commits in order might be easier

Which issue(s) this PR fixes:

Fixes #

Does this PR introduce a user-facing change?:

NONE

[gauravkghildiyal]

/cc @mlavacca

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: gauravkghildiyal, mlavacca

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• ~~gwctl/OWNERS~~ [gauravkghildiyal]

Approvers can indicate their approval by writing /approve in a comment Approvers can cancel approval by writing /approve cancel in a comment

[robscott]

Thanks @gauravkghildiyal!

/lgtm