3.0.0

This is a major release for kube-applier, redesigning the internals to work with kubernetes Custom Resources.

On a high level:

• A new CRD is introduced, Waybill: it defines the source of manifest files as well as options related to applying them (these were mostly defined as namespace annotations previously)
• There are no more "batch" runs. Each Waybill (which corresponds to a namespace) is applied independently of others.
• Improved performance with faster, parallel runs.
• Run results are captured in the status subresource and is accessible with kubectl.
• Various issues that can occur before an attempt is made to apply a namespace are surfaced as events and the last attempted run is retained in the status subresource.
• More flexible integration with strongbox for encrypted file support per namespace. Each Waybill can define its own keys to use for its sources.
• Use delegate ServiceAccounts for applying resources. The ServiceAccount of kube-applier has limited access to resources (see the ClusterRole provided in the "cluster" kustomize base).
• kustomize bases are provided for the kube-applier deployment and required cluster-level resources, as well as for client namespaces. Default values have been set where possible to make adoption as simple as possible, while allowing customization for more complex setups.
• Improved logs and metrics.
• Tests are not using mock interfaces anymore but build on the envtest package and run against a local apiserver.