android: support tailnet display name, falling back to domain

Updates https://github.com/tailscale/corp/issues/30456

Signed-off-by: Nick O'Neill <nick@tailscale.com>

android/src/main/java/com/tailscale/ipn/ui/model/TailCfg.kt

@@ -188,7 +188,15 @@ class Tailcfg {
   data class Service(var Proto: String, var Port: Int, var Description: String? = null)
 
   @Serializable
-  data class NetworkProfile(var MagicDNSName: String? = null, var DomainName: String? = null)
+  data class NetworkProfile(
+      var MagicDNSName: String? = null,
+      var DomainName: String? = null,
+      var DisplayName: String? = null
+  ) {
+      fun tailnetNameForDisplay(): String? {
+          return DisplayName ?: DomainName
+      }
+  }
 
   @Serializable
   data class Location(

android/src/main/java/com/tailscale/ipn/ui/view/MainView.kt

@@ -167,7 +167,7 @@ fun MainView(
                   }
                 },
                 headlineContent = {
-                  user?.NetworkProfile?.DomainName?.let { domain ->
+                  user?.NetworkProfile?.tailnetNameForDisplay()?.let { domain ->
                     AutoResizingText(
                         text = domain,
                         style = MaterialTheme.typography.titleMedium.short,
@@ -500,7 +500,7 @@ fun ConnectView(
               fontWeight = FontWeight.SemiBold,
               textAlign = TextAlign.Center,
               fontFamily = MaterialTheme.typography.titleMedium.fontFamily)
-          val tailnetName = user.NetworkProfile?.DomainName ?: ""
+          val tailnetName = user.NetworkProfile?.tailnetNameForDisplay() ?: ""
           Text(
               buildAnnotatedString {
                 append(stringResource(id = R.string.connect_to_tailnet_prefix))

android/src/main/java/com/tailscale/ipn/ui/view/UserView.kt

@@ -63,7 +63,7 @@ fun UserView(
           supportingContent = {
             Column {
               AutoResizingText(
-                  text = profile.NetworkProfile?.DomainName ?: "",
+                  text = profile.NetworkProfile?.tailnetNameForDisplay() ?: "",
                   style = MaterialTheme.typography.bodyMedium.short,
                   minFontSize = MaterialTheme.typography.minTextSize,
                   overflow = TextOverflow.Ellipsis)