Backport base Form style from Compound. (#1009)

Apply to all screens using the formBackground colour.

ElementX/Sources/Screens/CreateRoom/View/CreateRoomScreen.swift

@@ -28,8 +28,7 @@ struct CreateRoomScreen: View {
     var body: some View {
         mainContent
             .scrollDismissesKeyboard(.immediately)
-            .scrollContentBackground(.hidden)
-            .background(Color.element.formBackground.ignoresSafeArea())
+            .elementFormStyle()
             .navigationTitle(L10n.screenCreateRoomTitle)
             .navigationBarTitleDisplayMode(.inline)
             .toolbar {

ElementX/Sources/Screens/DeveloperOptionsScreen/View/DeveloperOptionsScreen.swift

@@ -85,8 +85,7 @@ struct DeveloperOptionsScreen: View {
             }
         }
         .overlay(effectsView)
-        .scrollContentBackground(.hidden)
-        .background(Color.element.formBackground.ignoresSafeArea())
+        .elementFormStyle()
         .navigationTitle(L10n.commonDeveloperOptions)
         .navigationBarTitleDisplayMode(.inline)
     }

ElementX/Sources/Screens/InviteUsersScreen/View/InviteUsersScreen.swift

@@ -22,8 +22,7 @@ struct InviteUsersScreen: View {
     
     var body: some View {
         mainContent
-            .scrollContentBackground(.hidden)
-            .background(Color.element.formBackground.ignoresSafeArea())
+            .elementFormStyle()
             .navigationTitle(L10n.screenCreateRoomActionInvitePeople)
             .navigationBarTitleDisplayMode(.inline)
             .toolbar {

ElementX/Sources/Screens/RoomDetailsEditScreen/View/RoomDetailsEditScreen.swift

@@ -27,8 +27,7 @@ struct RoomDetailsEditScreen: View {
     
     var body: some View {
         mainContent
-            .scrollContentBackground(.hidden)
-            .background(Color.element.formBackground.ignoresSafeArea())
+            .elementFormStyle()
             .scrollDismissesKeyboard(.immediately)
             .navigationTitle(L10n.screenRoomDetailsEditRoomTitle)
             .navigationBarTitleDisplayMode(.inline)

ElementX/Sources/Screens/RoomDetailsScreen/View/RoomDetailsScreen.swift

@@ -41,8 +41,7 @@ struct RoomDetailsScreen: View {
                 leaveRoomSection
             }
         }
-        .scrollContentBackground(.hidden)
-        .background(Color.element.formBackground.ignoresSafeArea())
+        .elementFormStyle()
         .alert(item: $context.alertInfo) { $0.alert }
         .alert(item: $context.leaveRoomAlertItem,
                actions: leaveRoomAlertActions,

ElementX/Sources/Screens/RoomMemberDetailsScreen/View/RoomMemberDetailsScreen.swift

@@ -27,8 +27,7 @@ struct RoomMemberDetailsScreen: View {
                 blockUserSection
             }
         }
-        .scrollContentBackground(.hidden)
-        .background(Color.element.formBackground.ignoresSafeArea())
+        .elementFormStyle()
         .alert(item: $context.ignoreUserAlert, actions: blockUserAlertActions, message: blockUserAlertMessage)
         .errorAlert(item: $context.errorAlert)
     }

ElementX/Sources/Screens/StartChatScreen/View/StartChatScreen.swift

@@ -28,8 +28,7 @@ struct StartChatScreen: View {
                 searchContent
             }
         }
-        .scrollContentBackground(.hidden)
-        .background(Color.element.formBackground.ignoresSafeArea())
+        .elementFormStyle()
         .navigationTitle(L10n.actionStartChat)
         .navigationBarTitleDisplayMode(.inline)
         .toolbar {