lnd: pass context to newServer and server.Start

In preparation for starting to thread a single parent context through
LND, we update the main `server.Start` method to take a context so that
it can later pass it to any subsytem's Start method it calls. We also
pass the context to `newServer` since it makes some calls that will
eventually reach the DB (for example the graph db).

lnd.go

@@ -626,7 +626,7 @@ func Main(cfg *Config, lisCfg ListenerCfg, implCfg *ImplementationCfg,
 	// Set up the core server which will listen for incoming peer
 	// connections.
 	server, err := newServer(
-		cfg, cfg.Listeners, dbs, activeChainControl, &idKeyDesc,
+		ctx, cfg, cfg.Listeners, dbs, activeChainControl, &idKeyDesc,
 		activeChainControl.Cfg.WalletUnlockParams.ChansToRestore,
 		multiAcceptor, torController, tlsManager, leaderElector,
 		implCfg,
@@ -758,7 +758,7 @@ func Main(cfg *Config, lisCfg ListenerCfg, implCfg *ImplementationCfg,
 	// case the startup of the subservers do not behave as expected.
 	errChan := make(chan error)
 	go func() {
-		errChan <- server.Start()
+		errChan <- server.Start(ctx)
 	}()
 
 	defer func() {