Migrate to kubebuilder go/v4

[ultram4rine]

Closes #421

📑 Description

Steps:

mv k8sgpt-operator k8sgpt-operator-orig
mkdir k8sgpt-operator && cd k8sgpt-operator
go mod init github.com/k8sgpt-ai/k8sgpt-operator
kubebuilder init --domain k8sgpt.ai --plugins=go/v4,grafana.kubebuilder.io/v1-alpha
cp -r ../k8sgpt-operator-orig/hack .
kubebuilder create api --group core --version v1alpha1 --kind K8sGPT # Resource: yes, Controller: yes
kubebuilder create api --group core --version v1alpha1 --kind Result # Resource: yes, Controller: no

Then copy file by file to new project layout.

✅ Checks

• My pull request adheres to the code style of this project
• My code requires changes to the documentation
• I have updated the documentation as required
• All the tests have passed

ℹ Additional Information

As kubebuilder scaffolded with golangci config I've also added a GH job with it.
Ways to fix this CI step:

• Configuration can be changed.
• Linter can be removed.
• Errors can be fixed as well, since there are some deprecated things (k8s.io/utils/pointer and grpc.WithInsecure).

Also made all k8s imports in form like corev1.