Decouple templates

Right now we keep all templates in a single location under pkg/features. We should revise this approach and use dedicated locations for each component/features it defines. Instead of a single //go:embed we can pass particular folder.

Perhaps simple convention of having feature_templates.go file for each component alongside with the folder can suffice.

feature_templates.go can serve as one stop shop providing, e.g.:

• all needed paths
• embedded fs with relevant templates

This separation makes `ManifestSource` a mandator step in the feature builder call chain.