Upon pod startup, update the Status of CredentialIssuerConfig

- Indicate the success or failure of the cluster signing key strategy
- Also introduce the concept of "capabilities" of an integration test
  cluster to allow the integration tests to be run against clusters
  that do or don't allow the borrowing of the cluster signing key
- Tests that are not expected to pass on clusters that lack the
  borrowing of the signing key capability are now ignored by
  calling the new library.SkipUnlessClusterHasCapability test helper
- Rename library.Getenv to library.GetEnv
- Add copyrights where they were missing

test/library/env.go

@@ -12,9 +12,9 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-// Getenv gets the environment variable with key and asserts that it is not
+// GetEnv gets the environment variable with key and asserts that it is not
 // empty. It returns the value of the environment variable.
-func Getenv(t *testing.T, key string) string {
+func GetEnv(t *testing.T, key string) string {
 	t.Helper()
 	value := os.Getenv(key)
 	require.NotEmptyf(t, value, "must specify %s env var for integration tests", key)