Refactor CAPI assets/manifests generator tool

User Story

As an OpenShift engineer I want to be able to install the new manifest generation tool as a standalone tool in my CAPI Infra Provider repo to generate the CAPI Provider transport ConfigMap(s)

Background

Renaming of the CAPI Asset/Manifest generator from assets (generator) to manifest-gen, as it won't need to generate go embeddable assets anymore, but only manifests that will be referenced and applied by CVO

Steps

• Removal of the `/assets` folder - we are moving away from embedded assets in favour of transport ConfigMaps
• Renaming of the CAPI Asset/Manifest generator from assets (generator) to manifest-gen, as it won't need to generate go embeddable assets anymore, but only manifests that will be referenced and applied by CVO

• Removal of the cluster-api-operator specific code from the assets generator - we are moving away from using the cluster-api-operator
• Remove the assets generator specific references from the Makefiles/hack scripts - they won't be needed anymore as the tool will be referenced only from other repositories 
• Adapting the new generator tool to be a standalone go module that can be installed as a tool in other repositories to generate manifests
• Make sure to add CRDs and Conversion,Validation (also Mutation?) Webhooks to the generated transport ConfigMaps

Stakeholders

• Cluster Infrastructure Team
• ShiftStack Team (CAPO)

Definition of Done

• Working and standalone installable generation tool