Refactor integration E2E tests

* General cleanup of the integration tests Golang code. Move the
  `e2e.go` codebase into its own package and separate files.
* Reduce the overall log spam from the integration tests output.
* Add final GitHub workflow step that stops GARM server, and does the
  GitHub cleanup of any orphaned resources.
* Add `TODO` to implement cleanup of the orphaned GitHub webhooks.
  This is useful, if the uninstall of the webhooks failed.
* Add `TODO` for extra missing checks on the GitHub webhooks
  install / uninstall logic.

Signed-off-by: Ionut Balutoiu <ibalutoiu@cloudbasesolutions.com>

test/integration/gh_cleanup/main.go

@@ -0,0 +1,34 @@
+package main
+
+import (
+	"log"
+	"os"
+
+	"github.com/cloudbase/garm/test/integration/e2e"
+)
+
+var (
+	orgName  = os.Getenv("ORG_NAME")
+	repoName = os.Getenv("REPO_NAME")
+
+	ghToken = os.Getenv("GH_TOKEN")
+)
+
+func main() {
+	controllerID, ctrlIdFound := os.LookupEnv("GARM_CONTROLLER_ID")
+	if ctrlIdFound {
+		_ = e2e.GhOrgRunnersCleanup(ghToken, orgName, controllerID)
+		_ = e2e.GhRepoRunnersCleanup(ghToken, orgName, repoName, controllerID)
+	} else {
+		log.Println("Env variable GARM_CONTROLLER_ID is not set, skipping GitHub runners cleanup")
+	}
+
+	baseURL, baseUrlFound := os.LookupEnv("GARM_BASE_URL")
+	if ctrlIdFound && baseUrlFound {
+		log.Printf("TODO: Cleanup org & repo webhooks staring with: %s/webhooks/%s", baseURL, controllerID)
+		// TODO: Cleanup org webhooks that start with "{baseURL}/webhooks/{controllerID}"
+		// TODO: Cleanup repo webhooks that start with "{baseURL}/webhooks/{controllerID}"
+	} else {
+		log.Println("Env variables GARM_CONTROLLER_ID & GARM_BASE_URL are not set, skipping webhooks cleanup")
+	}
+}