Move the route proxy into its module and run it from the trust image, on mesh-sdk's public membership (issues 1633, 1634, 1635)

A bundle is built only from its module's directory (ADR 0480 clause 4), so the proxy leaves
examples/ and the controller's internal/broker; the broker keeps no second copy of what the
proxy shares with mesh-sdk. The image and its Dockerfile go, and a test holds that only
build-agent declares one (clause 11).

modules/route-proxy/vendor/github.com/nats-io/nats.go/timer.go

@@ -0,0 +1,56 @@
+// Copyright 2017-2022 The NATS Authors
+// 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 nats
+
+import (
+	"sync"
+	"time"
+)
+
+// global pool of *time.Timer's. can be used by multiple goroutines concurrently.
+var globalTimerPool timerPool
+
+// timerPool provides GC-able pooling of *time.Timer's.
+// can be used by multiple goroutines concurrently.
+type timerPool struct {
+	p sync.Pool
+}
+
+// Get returns a timer that completes after the given duration.
+func (tp *timerPool) Get(d time.Duration) *time.Timer {
+	if t, ok := tp.p.Get().(*time.Timer); ok && t != nil {
+		t.Reset(d)
+		return t
+	}
+
+	return time.NewTimer(d)
+}
+
+// Put pools the given timer.
+//
+// There is no need to call t.Stop() before calling Put.
+//
+// Put will try to stop the timer before pooling. If the
+// given timer already expired, Put will read the unreceived
+// value if there is one.
+func (tp *timerPool) Put(t *time.Timer) {
+	if !t.Stop() {
+		select {
+		case <-t.C:
+		default:
+		}
+	}
+
+	tp.p.Put(t)
+}