Remove Sidebar FF and WPSplitViewController with related code

Modules/Sources/WordPressUI/Extensions/UIViewController+Helpers.swift

@@ -55,4 +55,8 @@ extension UIViewController {
     public static var topViewController: UIViewController? {
         UIApplication.shared.delegate?.window??.topmostPresentedViewController
     }
+
+    @objc public var splitViewControllerIsHorizontallyCompact: Bool {
+        splitViewController?.hasHorizontallyCompactView() ?? hasHorizontallyCompactView()
+    }
 }

WordPress/Classes/System/MySitesCoordinator+RootViewPresenter.swift

@@ -36,19 +36,11 @@ extension MySitesCoordinator: RootViewPresenter {
     // MARK: Me
 
     var meViewController: MeViewController? {
-        /// On iPhone, the My Sites root view controller is a navigation controller, and Me is pushed onto the stack
         if let navigationController = rootViewController as? UINavigationController,
            let controller = navigationController.viewControllers.compactMap({ $0 as? MeViewController }).first {
                return controller
            }
 
-        /// On iPad, the My Sites root view controller is a split view controller, and Me is shown in the detail view controller
-        if let splitViewController = rootViewController as? WPSplitViewController,
-           let detailNavigationController = splitViewController.viewControllers.last as? UINavigationController,
-           let controller = detailNavigationController.viewControllers.compactMap({ $0 as? MeViewController }).first {
-            return controller
-        }
-
         return nil
     }
 

WordPress/Classes/System/RootViewCoordinator.swift

@@ -91,7 +91,7 @@ class RootViewCoordinator {
     }
 
     private func createPresenter(_ appType: AppUIType) -> RootViewPresenter {
-        if UIDevice.isPad() && Feature.enabled(.sidebar) {
+        if UIDevice.isPad() {
             return SplitViewRootPresenter()
         }
         switch appType {

WordPress/Classes/Utility/BuildInformation/FeatureFlag.swift

@@ -13,7 +13,6 @@ enum FeatureFlag: Int, CaseIterable {
     case voiceToContent
     case authenticateUsingApplicationPassword
     case tipKit
-    case sidebar
     case newGutenberg
     case newGutenbergThemeStyles
     case newGutenbergPlugins
@@ -48,8 +47,6 @@ enum FeatureFlag: Int, CaseIterable {
             return false
         case .tipKit:
             return true
-        case .sidebar:
-            return true
         case .newGutenberg:
             return false
         case .newGutenbergThemeStyles:
@@ -91,7 +88,6 @@ extension FeatureFlag {
         case .voiceToContent: "Voice to Content"
         case .authenticateUsingApplicationPassword: "Application Passwords for self-hosted sites"
         case .tipKit: "TipKit"
-        case .sidebar: "Sidebar"
         case .newGutenberg: "Experimental Block Editor"
         case .newGutenbergThemeStyles: "Experimental Block Editor Styles"
         case .newGutenbergPlugins: "Experimental Block Editor Plugins"