Add encryption history banner and update session verification banner strings. (#1250)

* Add a hard wall on back-pagination in encrypted rooms.
Until the app supports key backup, the history will never be decryptable.

* Fix initial display of the timeline table view.

* Update session verification banner strings.

ElementX/Sources/Services/Timeline/TimelineItems/Items/Virtual/EncryptedHistoryRoomTimelineItem.swift

@@ -0,0 +1,21 @@
+//
+// Copyright 2023 New Vector Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import Foundation
+
+struct EncryptedHistoryRoomTimelineItem: DecorationTimelineItemProtocol, Identifiable, Hashable {
+    let id: String
+}

ElementX/Sources/Services/Timeline/TimelineItems/RoomTimelineItemView.swift

@@ -55,6 +55,8 @@ struct RoomTimelineItemView: View {
             UnsupportedRoomTimelineView(timelineItem: item)
         case .timelineStart(let item):
             TimelineStartRoomTimelineView(timelineItem: item)
+        case .encryptedHistory(let item):
+            EncryptedHistoryRoomTimelineView(timelineItem: item)
         case .state(let item):
             StateRoomTimelineView(timelineItem: item)
         case .group(let item):

ElementX/Sources/Services/Timeline/TimelineItems/RoomTimelineItemViewModel.swift

@@ -58,6 +58,7 @@ enum RoomTimelineItemType: Equatable {
     case sticker(StickerRoomTimelineItem)
     case unsupported(UnsupportedRoomTimelineItem)
     case timelineStart(TimelineStartRoomTimelineItem)
+    case encryptedHistory(EncryptedHistoryRoomTimelineItem)
     case state(StateRoomTimelineItem)
     case group(CollapsibleTimelineItem)
     case location(LocationRoomTimelineItem)
@@ -95,6 +96,8 @@ enum RoomTimelineItemType: Equatable {
             self = .unsupported(item)
         case let item as TimelineStartRoomTimelineItem:
             self = .timelineStart(item)
+        case let item as EncryptedHistoryRoomTimelineItem:
+            self = .encryptedHistory(item)
         case let item as StateRoomTimelineItem:
             self = .state(item)
         case let item as CollapsibleTimelineItem:
@@ -123,6 +126,7 @@ enum RoomTimelineItemType: Equatable {
              .sticker(let item as RoomTimelineItemProtocol),
              .unsupported(let item as RoomTimelineItemProtocol),
              .timelineStart(let item as RoomTimelineItemProtocol),
+             .encryptedHistory(let item as RoomTimelineItemProtocol),
              .state(let item as RoomTimelineItemProtocol),
              .group(let item as RoomTimelineItemProtocol),
              .location(let item as RoomTimelineItemProtocol):
@@ -137,7 +141,7 @@ enum RoomTimelineItemType: Equatable {
             return true
         case .redacted, .encrypted, .unsupported, .state: // Event based items that aren't reactable
             return false
-        case .timelineStart, .separator, .readMarker, .paginationIndicator: // Virtual items are never reactable
+        case .timelineStart, .encryptedHistory, .separator, .readMarker, .paginationIndicator: // Virtual items are never reactable
             return false
         case .group:
             return false