Implement gwctl describe namespaces

[gauravkghildiyal]

We ideally want to have something like this as the output for gwctl describe namespace my-namespace

Name: my-namespace
Labels: 
- key1: value1
- key2: value2
Annotations: 
- key1: value1
- key2: value2
Status: Active
DirectlyAttachedPolicies:
  TYPE                   NAME
  ----                   ----
  TimeoutPolicy.foo.com  demo-timeout-policy-on-namespace
  RetryOnPolicy.baz.com  demo-retry-policy-1

If it makes things easy, to start with, you can ignore the Label, Annotation and Status fields and do that in a follow up PR (once you are somewhat comfortable with the codebase). FYI: Adding those fields involves adding a Namespace resource (instead of the just the name) to the Namespace node, and then populating it within the discoverNamespaces

[gauravkghildiyal]

/area gwctl
/assign @Devaansh-Kumar

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/area gwctl
/assign @Devaansh-Kumar

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[gauravkghildiyal]

@Devaansh-Kumar -- Please use "/assign" to assign this to yourself. Do reach out if you get stuck somewhere

[Devaansh-Kumar]

/assign

[Devaansh-Kumar]

@gauravkghildiyal I have some confusions regarding how to phrase the command.

1. Ideally we want to use the command in the following way: gwctl describe namespace my-namespace. If the user types just gwctl describe namespace should be describe all the namespaces available or just return an error asking to specify a namespace? And what should the behavior be if -n flag is used? According me having -n flag does not make sense.
2. For just the namespace name and DirectlyAttachedPolicies, should I create a function like DiscoverResourcesForNamespace in discover.go?

[gauravkghildiyal]

@Devaansh-Kumar Those are valid questions.

1. Yes you are right, for gwctl describe namespace, we will describe all namespaces. I think what will help you here is that we're trying to match the behaviour of kubectl. Similar to kubectl, -n flag is redundant for namespaces.
2. Yes you are on the right track.

[gauravkghildiyal]

You don't need to use unstructured for namespaces -- simply use the k8sClients.Client to fetch a concrete corev1.Namespace typed resource.

In other words:

1. Fetch all namespaces
2. Wrap them in their respective nodes (inside addNamespace)