TestManager: Ensure no resources are in the cluster before deleting the namespace

[ecpullen]

Issue number:

N/A

Description of changes:

Author: ecpullen <[email protected]>
Date:   Thu Feb 9 18:06:32 2023 +0000

    cli: Print underlying errors with anyhow

Show the underlying error when a command fails.

Author: ecpullen <[email protected]>
Date:   Thu Feb 9 17:57:00 2023 +0000

    TestManager: Ensure no resources for uninstall
    
    If a resource is present in the cluster while the namespace is being
    deleted, there is a chance the resource deletion fails and puts the
    cluster in a bad state. To prevent that, all resources must be deleted
    before the namespace is deleted.

Testing done:

cli install followed by cli uninstall

With resources:

$ cli uninstall
Unable to uninstall testsys from the cluster. (Some artifacts may be left behind)

Caused by:
    Some resources are still in the cluster

After the resources are cleaned up:

$ cli uninstall
testsys components were successfully uninstalled.

Terms of contribution:

By submitting this pull request, I agree that this contribution is dual-licensed under the terms of both the Apache License, version 2.0, and the MIT license.

[stmcginnis]

Looks good to me. One minor thing pointed out, but I think it's fine as is.