v6.0.0-beta.24

• Added InAppWebView keep alive feature
• Added InAppBrowser menu items feature
• Added hasJavaScriptHandler, hasUserScript, hasWebMessageListener InAppWebViewController methods
• Added hideCloseButton, hideDefaultMenuItems, menuButtonColor InAppBrowser settings
• HeadlessInAppWebView.webViewController could be null
• Removed throwIfAlreadyOpened, throwIfNotOpened InAppBrowser methods
• Removed throwIfAlreadyOpened, throwIfNotOpened ChromeSafariBrowser methods
• Merged "fix #1389 #1315 contextMenu ios 13" #1575 (thanks to heralight)
• Merged "fix: remove ignored flutter_export_environment.sh" #1593 (thanks to Sunbreak)
• Merged "Fix AndroidX migration URL in README.md" #1529 (thanks to cslee)
• Merged "InAppBrowser Bugfix/viewgroup index crash" #1618 (thanks to KhatibFX)
• Fixed old iOS versions crash "dyld: Library not loaded: /usr/lib/swift/libswiftCoreGraphics.dylib Reason: image not found" (thanks to guide-flutter)
• Fixed InAppBrowser.show() possible crash on macOS
• Fixed missing windowTitlebarSeparatorStyle, windowAlphaValue, windowStyleMask, windowFrame macOS settings updates when using setSettings()
• Fixed "iOS and macOS flutter multiple engine" #1632