android/ui: use faster sliding animations for nav transitions

Updates tailscale/corp#18202

Signed-off-by: Percy Wegmann <percy@tailscale.com>

android/src/main/java/com/tailscale/ipn/MainActivity.kt

@@ -16,6 +16,9 @@ import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
 import androidx.activity.result.ActivityResultLauncher
 import androidx.activity.result.contract.ActivityResultContract
+import androidx.compose.animation.core.tween
+import androidx.compose.animation.slideInHorizontally
+import androidx.compose.animation.slideOutHorizontally
 import androidx.lifecycle.lifecycleScope
 import androidx.navigation.NavType
 import androidx.navigation.compose.NavHost
@@ -69,7 +72,21 @@ class MainActivity : ComponentActivity() {
     setContent {
       AppTheme {
         val navController = rememberNavController()
-        NavHost(navController = navController, startDestination = "main") {
+        NavHost(
+            navController = navController,
+            startDestination = "main",
+            enterTransition = {
+              slideInHorizontally(animationSpec = tween(150), initialOffsetX = { it })
+            },
+            exitTransition = {
+              slideOutHorizontally(animationSpec = tween(150), targetOffsetX = { -it })
+            },
+            popEnterTransition = {
+              slideInHorizontally(animationSpec = tween(150), initialOffsetX = { -it })
+            },
+            popExitTransition = {
+              slideOutHorizontally(animationSpec = tween(150), targetOffsetX = { it })
+            }) {
               val mainViewNav =
                   MainViewNavigation(
                       onNavigateToSettings = { navController.navigate("settings") },
@@ -132,7 +149,9 @@ class MainActivity : ComponentActivity() {
               composable("userSwitcher") {
                 UserSwitcherView(
                     nav = backNav,
-                onNavigateHome = { navController.popBackStack(route = "main", inclusive = false) })
+                    onNavigateHome = {
+                      navController.popBackStack(route = "main", inclusive = false)
+                    })
               }
               composable("permissions") {
                 PermissionsView(nav = backNav, openApplicationSettings = ::openApplicationSettings)