Fixes test app verify for running with KinD on a MacOS

[diverdane]

When the Kubernetes Conjur demo scripts are run on a Kubernetes-in-Docker cluster
that is running on MacOS, then the demo script verification that the demo API
endpoints are reachable (check-url function) currently fails:

curl: (28) Connection timed out after 3003 milliseconds
'check_urls' Retry 5/150 exited 28, retrying in 2 seconds...

The problem is that using Node-IP:NodePort does not work for KinD on MacOS
because Docker on MacOS runs Docker containers inside a VM, so there is no
direct way to connect from the MacOS host to Kubernetes containers.

The fix is to add the creation of a test-curl pod in the test application namespace
that is capable of running curl from within the KinD cluster, and then using this
to verify applications using their internal service address.

This change also replaces the test environment variable TEST_APP_NODEPORT_SVCS
(defaults to false) with TEST_APP_LOADBALANCER_SVCS (defaults to true)
because that more accurately reflects what needs to be distinguished
(i.e. if there aren't any load balancers, the test application service type could
be either NodePort or clusterIP, since the test app verification is now
agnostic of NodePort vs clusterIP services.

Addresses Issue #117

[BradleyBoutcher]

LGTM! Thanks for fixing this!

[BradleyBoutcher]

I'd be in favor of using a loop here for building the URL and subsequently querying all the containers, but I think that's out of the scope for this issue.

i.e. we could retrieve all the relevant URLs with

applications=$(kubectl get services -n ${TEST_APP_NAMESPACE_NAME} \
                        --template '{{range .items}}{{.metadata.name}}{{"\n"}}{{end}}' \
                        | grep -p init )

or

applications=$(kubectl get services -n ${TEST_APP_NAMESPACE_NAME} \
                        --template '{{range .items}}{{.metadata.name}}{{"\n"}}{{end}}' \
                        | grep -p test-app )

Then perform a loop like this:

for app in $applications; do 
    APPLICATION_URL="http://${app}.${TEST_APP_NAMESPACE_NAME}.svc.cluster.local:8080"
done