Support for tenancy=host with 1 instance - 1 host relation

[enxebre]

/kind feature

Describe the solution you'd like
As a Service Consumer I want to be able to leverage dedicated hosts for BYOL scenarios.
As a Service Consumer I want to express intent for 1 - 1 relation between instance and host with matching capacity so I don’t need to carry the burden of reservations out of band.
As capi/capa API consumer I want capa to expose a knob so I can express intent for this use case. It would discover the most efficient reservation out of my instance type, create the reservation and pin the instance to it at run time

Anything else you would like to add:

Similar to #5548 but covering a different use case. Both complementary.

Environment:

• Cluster-api-provider-aws version:
• Kubernetes version: (use kubectl version):
• OS (e.g. from /etc/os-release):

[k8s-ci-robot]

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