Extract Kubectl executor feature as a plugin

[huseyinbabal]

Overview

Botkube supports kubectl execution and it is a typical Executor plugin. We need to extract it as a standalone plugin.

Acceptance Criteria

• Extract kubectl executor as a plugin and maintain it Botkube main repository
• Ensure it is backward compatible.
• Plugin parameters will be documented in the plugin's README.md page, and they can be provided from Botkube as an environment variable like KUBERNETES_... so that they can be passed to the executable in this line
• Remember about interactivity
• Update gRPC executor API
• Make sure anonymized telemetry is still supported - we can lose some data, but confirm with @brampling if we can do that
• Update the document

Additional scope / notes

• Ensure it supports the RBAC design according to Role-Based Access Control #712 (design https://github.com/kubeshop/botkube/blob/main/docs/proposal/2022-12-23-rbac.md), if Handle passing Kubeconfig to plugins (Executor and Sources) #934 is already done. If not, ensure we can easily support this in the plugin.

[pkosiec]

See @mszostok's PR: #862

[mszostok]

Implementation:

• Add kubectl plugin to run directly typed kubectl commands #973
• Add interactive builder in kubectl plugin #982
• Add msg interactivity example, use pluginx botkube-plugins-template#12
• Remove built-in kubectl from the code-base, adjust e2e tests to use plugin version #986

Docs:

• Adjust kubectl docs to reflect plugin approach botkube-docs#213
• Describe interactive message building blocks botkube-docs#215

[mszostok]

The kubectl plugin was implemented. The only thing that left is to replace it in the e2e tests after adding RBAC support: #1003