Add conditional for starting adoption reconciler

[RedbackThomson]

Issue #, if available: aws-controllers-k8s/community#1006

Description of changes:
Use cluster introspection to determine whether the AdoptedResource CRD has been installed, starting the adoption reconciler only if they have been. This will allow cluster operators to intentionally leave the AdoptedResource uninstalled, if they wish to handle this separately.

I have tested these changes by uninstalling the AdoptedResource CRD and then running the controller. I see the following line in the logs to prove it is working:

2021-10-19T14:52:42.975-0700    INFO    adoption  AdoptedResource CRD not installed. The adoption reconciler will not be started

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[acornett21]

@RedbackThomson Here are my test results from a 4.8 OpenShift cluster.

Without AdoptedResource applied to a cluster

2021-10-20T17:11:01.936Z        DEBUG   cache.account   created account config map      {"name": "ack-role-account-map"}
2021-10-20T17:11:01.943Z        INFO    adoption-setup  AdoptedResource CRD not installed. The adoption reconciler will not be started
2021-10-20T17:11:01.943Z        INFO    setup   starting manager        {"aws.service": "elasticache"}

Applying the AdoptedResource CRD to the cluster and then restarting the controller pod

2021-10-20T17:15:35.811Z        INFO    controller-runtime.controller   Starting Controller     {"controller": "adoptedresource"}
2021-10-20T17:15:35.811Z        INFO    controller-runtime.controller   Starting workers        {"controller": "adoptedresource", "worker count": 1}

Uninstalling the operator and leaving the AdoptedResource CRD applied to the cluster, then reinstalling the operator

2021-10-20T17:21:10.204Z        INFO    controller-runtime.controller   Starting Controller     {"controller": "adoptedresource"}
2021-10-20T17:21:10.204Z        INFO    controller-runtime.controller   Starting workers        {"controller": "adoptedresource", "worker count": 1}

I think this solves the issue and didn't see any problems with testing. If you would like something else tested please let me know.

[vijtrip2]

/lgtm

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