As an OpenShift Windows admin, I would like the WMCO to create config files compatible with containerd, so that my cluster's mirror settings are applied to Windows nodes.

Description

This story covers generating host.toml files based on a cluster's mirror registry settings. This will involve introducing a "registry controller" to WMCO which watches to ImageDigestMirrorSet and ImageTagMirrorSet resources. The controller should generate a set of containerd config files when cluster settings are updated.

We can utilize [registry runtime-utils](https://github.com/openshift/runtime-utils/blob/master/pkg/registries/registries.go) to easily process and merge the contents of the IDMS/ITMS resources, [as MCO does](https://github.com/openshift/machine-config-operator/blob/master/pkg/controller/container-runtime-config/helpers.go#L407). This will help us to generate config file content from a unified object representing the cluster's mirror registry configuration state.

Acceptance Criteria

• WMCO watches IDMS/ITMS resources
• WMCO translates cluster's image mirror settings to containerd compatible hosts.toml files
• Unit testing for the registry controller must cover both the file content and verifying that it is reactive to changes in IDMS/ITMS resources