cmd/osbuild-worker-executor: import verbatim from mvo5/oaas

This commit imports the repository https://github.com/mvo5/oaas
without keeping the history. The history is largely unimportant
and can be looked up in https://github.com/mvo5/oaas/commits/main
if needed.

cmd/osbuild-worker-executor/handler_root_test.go

@@ -0,0 +1,18 @@
+package main_test
+
+import (
+	"net/http"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestTrivialRootEndpoint(t *testing.T) {
+	baseURL, _, loggerHook := runTestServer(t)
+
+	endpoint := baseURL
+	resp, err := http.Get(endpoint)
+	assert.NoError(t, err)
+	assert.Equal(t, resp.StatusCode, 200)
+	assert.Equal(t, loggerHook.LastEntry().Message, "/ handler called")
+}