Add Welcome screen

Shared/Views/WelcomeScreen.swift

@@ -0,0 +1,63 @@
+import SwiftUI
+
+struct WelcomeScreen: View {
+    @Environment(\.dismiss) private var dismiss
+
+    @EnvironmentObject<AccountsModel> private var accounts
+    @EnvironmentObject<NavigationModel> private var navigation
+
+    var body: some View {
+        VStack {
+            Spacer()
+
+            Text("Welcome")
+                .font(.largeTitle)
+                .padding(.bottom, 10)
+
+            if accounts.all.isEmpty {
+                Text("To start, configure your Instances in Settings")
+                    .foregroundColor(.secondary)
+            } else {
+                Text("To start, pick one of your accounts:")
+                    .foregroundColor(.secondary)
+                #if os(tvOS)
+                    AccountSelectionView(showHeader: false)
+
+                    Button {
+                        dismiss()
+                    } label: {
+                        Text("Start")
+                    }
+                    .opacity(accounts.account.isNil ? 0 : 1)
+                    .disabled(accounts.account.isNil)
+
+                #else
+                    AccountsMenuView()
+                        .onChange(of: accounts.account) { _ in
+                            dismiss()
+                        }
+                    #if os(macOS)
+                        .frame(maxWidth: 280)
+                    #endif
+                #endif
+            }
+
+            Spacer()
+
+            OpenSettingsButton()
+
+            Spacer()
+        }
+        .interactiveDismissDisabled()
+        #if os(macOS)
+            .frame(minWidth: 400, minHeight: 400)
+        #endif
+    }
+}
+
+struct WelcomeScreen_Previews: PreviewProvider {
+    static var previews: some View {
+        WelcomeScreen()
+            .injectFixtureEnvironmentObjects()
+    }
+}