The e2e core framework and subpackages of e2e framework are defined.
The subpackages can import the core framework, but the core framework
should not import the subpackages. We've defined this dependency rule
after circular depencency issue happened.
This adds TODOs to understand what we should in this rule.
Remove the "OrDie" from the name (since it doesn't "or die") and add
an extra check that there is at least 1 node available, since many
callers already did that themselves, and many others should have.
it turns out that the framework.TestContext.IPFamily variable is
not available for the DNS tests if they don't run in the initial
Ginkgo node when running in parallel.
We add a function to the framework to allow us to run command
only once per each Ginkgo node parallel execution.
It also adds a method to detect if the cluster is IPv6.
The use of the framework.TestContext.IPFamily variable guarantees
consistency all over the testing because this variable is only
assigned at the beginning of the testing.
