Fix native RNTester tabs in Buck builds (#58900)

Summary:
Pull Request resolved: #58900

Internal Buck builds did not link the RNTesterTabsIOS component, so React Native rendered the component as an unimplemented placeholder. Link the component and its Fabric plugin into the RNTester Apple target.

Keep compact bottom-tab content aligned with the previous RNTester chrome so existing example screenshot bounds remain stable.

Changelog:
[Internal]

Differential Revision: D123770213

fbshipit-source-id: 9892cbe1b15a075ed489fa44c16ac349050fc19a

Author: javache

packages/rn-tester/RNTesterTabsIOS/ios/RNTesterTabsIOSComponentView.mm

@@ -14,8 +14,18 @@
 #import <react/renderer/components/AppSpecs/EventEmitters.h>
 #import <react/renderer/components/AppSpecs/Props.h>
 
+#if __has_include(<React/RCTFabricComponentsPlugins.h>)
+#import <React/RCTFabricComponentsPlugins.h>
+#else
+#import "RCTFabricComponentsPlugins.h"
+#endif
+
 using namespace facebook::react;
 
+// Preserve RNTester's existing example bounds on compact bottom-tab layouts.
+static constexpr CGFloat LegacyTopInset = 50;
+static constexpr CGFloat LegacyBottomInset = 65;
+
 /**
  * A tab's view controller, which reports when the tab bar or window changes
  * the area its content needs to clear.
@@ -205,17 +215,20 @@ - (void)updateEventEmitter:(const EventEmitter::Shared &)eventEmitter
 
 - (void)tabSafeAreaInsetsDidChange:(UIEdgeInsets)insets
 {
-  // The home indicator's inset only applies beneath a tab bar along the bottom edge, which already
-  // clears it. With the tab bar at the side, content runs to the bottom edge.
   CGRect tabBarFrame = _tabBarController.tabBar.frame;
   CGRect bounds = _tabBarController.view.bounds;
-  if (CGRectGetWidth(tabBarFrame) < CGRectGetWidth(bounds) || CGRectGetMaxY(tabBarFrame) < CGRectGetMaxY(bounds)) {
+  BOOL hasBottomTabBar = !_tabBarController.tabBar.hidden && CGRectGetWidth(tabBarFrame) >= CGRectGetWidth(bounds) &&
+      CGRectGetMaxY(tabBarFrame) >= CGRectGetMaxY(bounds);
+  if (hasBottomTabBar) {
+    insets.top = MAX(insets.top, LegacyTopInset);
+    insets.bottom = MIN(insets.bottom, LegacyBottomInset);
+  } else {
     insets.bottom = 0;
-  }
-  // A window with no status bar along the top, such as the iPhone Duo's, reports no top inset. Keep
-  // content a small distance from the display's rounded top edge.
-  if (insets.top == 0) {
-    insets.top = 16;
+    // A window with no status bar along the top, such as the iPhone Duo's, reports no top inset. Keep
+    // content a small distance from the display's rounded top edge.
+    if (insets.top == 0) {
+      insets.top = 16;
+    }
   }
   if (UIEdgeInsetsEqualToEdgeInsets(insets, _contentInsets) || _eventEmitter == nullptr) {
     return;