The HostClaim resource is introduced to address multi-tenancy in
Metal3 and the definition of hybrid clusters with cluster-api.

Introduces four scenarios representing the three main use cases and
how pivot is made.

Presentation of the design will be addressed in another merge request.

Co-authored-by: Pierre Crégut <pierre.cregut@orange.com>
Co-authored-by: Laurent Roussarie <laurent.roussarie@orange.com>
Signed-off-by: Pierre Crégut <pierre.cregut@orange.com>

Signed-off-by: Pierre Crégut <pierre.cregut@orange.com>

* security risks that must be addressed
* alternatives for the different use cases (multi tenancy or hybrid).

Co-authored-by: Pierre Crégut <pierre.cregut@orange.com>
Co-authored-by: Laurent Roussarie <laurent.roussarie@orange.com>

Signed-off-by: Pierre Crégut <pierre.cregut@orange.com>

The access to the remote cluster is pushed from a specific "remote"
HostClaim to the metal3 machine controller.
Risks of using a kubeconfig for automation are exposed.

Signed-off-by: Pierre Crégut <pierre.cregut@orange.com>

Consensus against from Metal3 dev team.

Signed-off-by: Pierre Crégut <pierre.cregut@orange.com>