control/controlclient: treat node sharer as owner for display purposes

This make clients (macOS, Windows, tailscale status) show the node
sharer's profile rather than the node owner (which may be anonymized).

Updates #992

control/controlclient/direct.go

@@ -785,6 +785,20 @@ func (c *Direct) sendMapRequest(ctx context.Context, maxPolls int, cb func(*Netw
 		}
 		addUserProfile(nm.User)
 		for _, peer := range resp.Peers {
+			// TODO(bradfitz): ideally we'd push down the semantically correct
+			// Nodes with differing User vs Sharer fields, but that means
+			// updating Windows, macOS, and tailscale status to respect all
+			// those fields, but until we have a plan for what the UI should
+			// be later when we treat them differently, it's easier to just
+			// merge it together here. The server will anonymize UserProfile
+			// records of those not in your network and not a sharer, which
+			// will be most of the peer.Users so it'll be rare when a node's
+			// owner-who's-different-from-sharer will have a non-scrubbed
+			// UserProfile: they would've also needed to share a node
+			// themselves.  Until we care, merge the data here.
+			if !peer.Sharer.IsZero() {
+				peer.User = peer.Sharer
+			}
 			addUserProfile(peer.User)
 		}
 		if resp.Node.MachineAuthorized {