Hide the unread dot after previewing an invite. (#3800)

* Hide the unread dot when previewing an invite.

* Remove an invited room ID when accepting/rejecting.

* Remove the unread badge from knocked room cells.

* Update snapshots.

* Address PR comments.

Refactor KnockRequestType to JoinRequestType.

UnitTests/Sources/RoomSummaryTests.swift

@@ -56,7 +56,7 @@ class RoomSummaryTests: XCTestCase {
     func makeSummary(isDirect: Bool, hasRoomAvatar: Bool) -> RoomSummary {
         RoomSummary(roomListItem: .init(noPointer: .init()),
                     id: roomDetails.id,
-                    knockRequestType: nil,
+                    joinRequestType: nil,
                     name: roomDetails.name,
                     isDirect: isDirect,
                     avatarURL: hasRoomAvatar ? roomDetails.avatarURL : nil,