Isolate Kogito Operator APIs into a new Go module and generate Kubernetes clients

Today is really hard for any third-party Kubernetes application to import Kogito Custom Resources to another go application.

Since Kogito Operator imports too many vendors, by importing the main module like github.com/kiegroup/kogito-operator for only using the Kogito custom resources, too many unneeded dependencies is carried over.

In this JIRA, we will provide a mechanism similar to Camel-K, whereas the api and client packages reside in exclusive modules. This way, third-party Go Kubernetes applications can only import these packages, not having to bring the entire dependency tree.

See: https://github.com/apache/camel-k/blob/v1.4.0/pkg/apis/camel/go.mod

About the clients, would be also nice to have the Kogito Custom Resources be capable to offer a typed API to communicate with the Kubernetes server. This is done automatically by kubebuilder, but need to be added to the repository as well, so others can import.