Today in KTF we manually step through all the pods/objects in the
cluster to get debug information. KIND now supports simply
running `kind export logs` which does a better job of giving us
a cluster debug overview. Switch the DumpDiagnostics function to
use this command for cluster log dumping instead.

Intentionally leave the logic which allows each addon to write their own
specific cleanup functionality.

Also continue to export the `kubectl_describe_all.txt` and `kubectl_get_all.yaml`
files for all cluster types.

Signed-off-by: Andrew Stoycos <astoycos@redhat.com>

Add new integration test for using `kind export logs` in DumpDiagnostics.
Update old addon test to use the new filepath for pod logs.

Signed-off-by: Andrew Stoycos <astoycos@redhat.com>

Add godoc comment to DumpAllDescribeAll function.

use t.cleanup instead of defer.

Signed-off-by: Andrew Stoycos <astoycos@redhat.com>

Standardize function signatures for all cluster diagnostics functions.

Standardize name of diagnostic output directory from a mixture of "output"
and "outDir" to just "outdir".

Signed-off-by: Andrew Stoycos <astoycos@redhat.com>