Add E2E tests for basic functionality and port launching to Go

This adds a new E2E test suite replacing the old log-parsing
based one. It also moves launching and controlling Smalltown VMs into
a Go package and command and exposes the '//:launch' alias.
The new E2E test suite covers basic conditions (IP assigned, Data
available) and Kubernetes Node, Deployment and StatefulSet tests.

Test Plan: This consists of E2E tests

X-Origin-Diff: phab/D544
GitOrigin-RevId: 7c624c667c849068bafa544a3a6c635d6d406e1c
diff --git a/core/tests/e2e/utils.go b/core/tests/e2e/utils.go
new file mode 100644
index 0000000..f888189
--- /dev/null
+++ b/core/tests/e2e/utils.go
@@ -0,0 +1,51 @@
+// Copyright 2020 The Monogon Project Authors.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package e2e
+
+import (
+	"context"
+	"errors"
+	"testing"
+	"time"
+)
+
+// testEventual creates a new subtest looping the given function until it either doesn't return an error anymore or
+// the timeout is exceeded. The last returned non-context-related error is being used as the test error.
+func testEventual(t *testing.T, name string, ctx context.Context, timeout time.Duration, f func(context.Context) error) {
+	ctx, cancel := context.WithTimeout(ctx, timeout)
+	t.Helper()
+	t.Run(name, func(t *testing.T) {
+		defer cancel()
+		var lastErr = errors.New("test didn't run to completion at least once")
+		t.Parallel()
+		for {
+			err := f(ctx)
+			if err == nil {
+				return
+			}
+			if err == ctx.Err() {
+				t.Fatal(lastErr)
+			}
+			lastErr = err
+			select {
+			case <-ctx.Done():
+				t.Fatal(lastErr)
+			case <-time.After(1 * time.Second):
+			}
+		}
+	})
+}