all: migrate code off Notify.NetMap to Notify.SelfChange

Move tailscaled's in-tree reactive users from of IPN bus Notify.NetMap
updates to the narrower Notify.SelfChange signal introduced earlier in
this series. Consumers that need additional state (peers, DNS config,
etc.) fetch it on demand via the LocalAPI.

It is a step toward the larger goal of not fanning Notify.NetMap out
to every bus watcher on Linux/non-GUI hosts.

A future change stops sending Notify.NetMap entirely on Linux and
non-GUI platforms. (eventually once macOS/iOS/Windows migrate to the
upcoming new Notify APIs, we'll remove ipn.Notify.NetMap entirely)

Updates #12542

Change-Id: I51ea9d86bdca1909d6ac0e7d5bd3934a3a4e8516
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

cmd/tailscale/cli/file.go

@@ -287,9 +287,9 @@ func runCp(ctx context.Context, args []string) error {
 // caller's progress display stays at 0 — exactly the right degradation,
 // since the warning timer will then fire on its normal 3-second deadline.
 func watchOutgoingFiles(ctx context.Context, peer tailcfg.StableNodeID, onUpdate func(name string, sent int64)) {
-	// NotifyPeerChanges asks the broadcaster to deliver incremental peer
-	// updates as small PeerChanges blobs in place of the full NetMap, which
-	// we don't read anyway. (See ipn/ipnlocal/local.go's notify-elision.)
+	// NotifyPeerChanges opts in to per-peer add/remove notifications so the
+	// bus stays responsive without us also subscribing to the full NetMap,
+	// which we don't read here.
 	w, err := localClient.WatchIPNBus(ctx, ipn.NotifyInitialOutgoingFiles|ipn.NotifyPeerChanges)
 	if err != nil {
 		return

cmd/tailscale/cli/serve_legacy.go

@@ -848,10 +848,10 @@ func (e *serveEnv) enableFeatureInteractive(ctx context.Context, feature string,
 			e.lc.IncrementCounter(ctx, fmt.Sprintf("%s_enablement_lost_connection", feature), 1)
 			return err
 		}
-		if nm := n.NetMap; nm != nil && nm.SelfNode.Valid() {
+		if self := n.SelfChange; self != nil {
 			gotAll := true
 			for _, c := range caps {
-				if !nm.SelfNode.HasCap(c) {
+				if _, has := self.CapMap[c]; !has {
 					// The feature is not yet enabled.
 					// Continue blocking until it is.
 					gotAll = false

cmd/tailscale/cli/up.go

@@ -732,7 +732,7 @@ func runUp(ctx context.Context, cmd string, args []string, upArgs upArgsT) (retE
 			if s := n.State; s != nil {
 				ipnIsRunning = *s == ipn.Running
 			}
-			if n.NetMap != nil && n.NetMap.NodeKey != origNodeKey {
+			if n.SelfChange != nil && n.SelfChange.Key != origNodeKey {
 				waitingForKeyChange = false
 			}
 			if ipnIsRunning && !waitingForKeyChange {