SMP merger and typeoverrides

New package: pkg/typeoverride

Types in this package are the structural equivalent of their original Kubernetes counterparts with the difference, that required fields are declared as optional using omitempty or in certain cases some fields are left off.

The purpose of this is that now these types can be embedded into CRDs and can be used to provide a convenient override mechanism for resources created inside an operator combined with the Merge function in pkg/merge

Breaking change

Changes the signature of the Merge function in pkg/merge and Unmarshal results directly into base.

Depractions

Base types in the pkg/types are now deprecated in favour of using pkg/typeoverride with pkg/merge

Tooling

Upgrade controller-gen to v0.4.1 and fix makefile to always use locally installed version