feat(ios): use UIBarButtonSystemItemClose since iOS 26 (#1138)

- Since iOS 13 it's possible to use `UIBarButtonSystemItemClose` instead of `UIBarButtonSystemItemDone` which correspond perfectly to a close button. Since `UIBarButtonSystemItemClose` looks akward on iOS 18 and older, because an X inside a round button is shown, instead of a text, the close button is only applied since iOS 26.

Co-authored-by: Copilot <copilot@github.com>

Author: GitToTheHub

src/ios/CDVWKInAppBrowser.m

@@ -38,6 +38,8 @@ Licensed to the Apache Software Foundation (ASF) under one
 
 #define    IAB_BRIDGE_NAME @"cordova_iab"
 
+#define    kCloseButtonSystemItem (@available(iOS 26.0, *) ? UIBarButtonSystemItemClose : UIBarButtonSystemItemDone)
+
 #pragma mark CDVWKInAppBrowser
 
 @implementation CDVWKInAppBrowser
@@ -811,7 +813,9 @@ - (void)createViews
 
     // NOTE: On iOS 26 using `UIBarButtonItem initWithBarButtonSystemItem:` gives constraint warnings,
     // which is a known UIKit bug.
-    self.closeButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(close)];
+    self.closeButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:kCloseButtonSystemItem
+                                                                     target:self
+                                                                     action:@selector(close)];
     self.closeButton.enabled = YES;
 
     UIBarButtonItem *flexibleSpaceButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];
@@ -1014,11 +1018,11 @@ - (void)setWebViewFrame:(CGRect)frame
 
 - (void)setCloseButtonTitle:(NSString *)title withColor:(NSString *)colorString atIndex:(int)buttonIndex
 {
-    // The advantage of using UIBarButtonSystemItemDone is the system will localize it for you automatically
-    // but, if you want to set this yourself, knock yourself out. (We can't set the title for a system Done button, so we have to create a new one.)
+    // The system Close/Done button title is localized automatically.
+    // If a custom caption is provided, create a title-based button instead.
     self.closeButton = nil;
-    // Initialize with title if title is set, otherwise the title will be 'Done' localized.
-    self.closeButton = title != nil ? [[UIBarButtonItem alloc] initWithTitle:title style:UIBarButtonItemStylePlain target:self action:@selector(close)] : [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(close)];
+    // Initialize with title if set, otherwise use the system-localized Close/Done item.
+    self.closeButton = title != nil ? [[UIBarButtonItem alloc] initWithTitle:title style:UIBarButtonItemStylePlain target:self action:@selector(close)] : [[UIBarButtonItem alloc] initWithBarButtonSystemItem:kCloseButtonSystemItem target:self action:@selector(close)];
     self.closeButton.enabled = YES;
     // If color on closebutton is requested then initialize with that that color, otherwise use initialize with default.
     self.closeButton.tintColor = colorString != nil ? [self colorFromHexString:colorString] : [UIColor colorWithRed:60.0 / 255.0 green:136.0 / 255.0 blue:230.0 / 255.0 alpha:1];