feat: add agent acks to in-memory coordinator (#12786)

When an agent receives a node, it responds with an ACK which is relayed
to the client. After the client receives the ACK, it's allowed to begin
pinging.

codersdk/workspacesdk/connector.go

@@ -86,9 +86,11 @@ func runTailnetAPIConnector(
 func (tac *tailnetAPIConnector) manageGracefulTimeout() {
 	defer tac.cancelGracefulCtx()
 	<-tac.ctx.Done()
+	timer := time.NewTimer(time.Second)
+	defer timer.Stop()
 	select {
 	case <-tac.closed:
-	case <-time.After(time.Second):
+	case <-timer.C:
 	}
 }
 

codersdk/workspacesdk/connector_internal_test.go

@@ -102,6 +102,8 @@ func (*fakeTailnetConn) SetNodeCallback(func(*tailnet.Node)) {}
 
 func (*fakeTailnetConn) SetDERPMap(*tailcfg.DERPMap) {}
 
+func (*fakeTailnetConn) SetTunnelDestination(uuid.UUID) {}
+
 func newFakeTailnetConn() *fakeTailnetConn {
 	return &fakeTailnetConn{}
 }