Swift migration

Just an overview of our ObjC files by size:

```
✗ find . -name "*.m" -print0 | xargs -0 stat -f "%z bytes %N" | sort -n -r
174749 bytes ./NCAPIController.m
125060 bytes ./RoomInfoTableViewController.m
81316 bytes ./RoomsTableViewController.m
72578 bytes ./NCCallController.m
46895 bytes ./NCSignalingMessage.m
45464 bytes ./NCChatController.m
39775 bytes ./NCNotificationController.m
38345 bytes ./NCRoomsManager.m
38286 bytes ./NCSettingsController.m
37727 bytes ./NCDatabaseManager.m
35006 bytes ./NCExternalSignalingController.m
29499 bytes ./CallKitManager.m
27677 bytes ./AppDelegate.m
27056 bytes ./NCChatMessage.m
23806 bytes ./NCUserInterfaceController.m
22126 bytes ./NCPeerConnection.m
21904 bytes ./AddParticipantsTableViewController.m
19002 bytes ./ShareLocationViewController.m
14922 bytes ./DirectoryTableViewController.m
13923 bytes ./LoginViewController.m
12604 bytes ./RoomSearchTableViewController.m
12411 bytes ./NCChatFileController.m
10992 bytes ./UIBarButtonItem+Badge.m
10013 bytes ./CallParticipantViewCell.m
9572 bytes ./NCContactsManager.m
9192 bytes ./NCRoom.m
8116 bytes ./VoiceMessageTranscribeViewController.m
7954 bytes ./ScreenCapturer.m
7923 bytes ./NCAppBranding.m
7869 bytes ./AuthenticationViewController.m
7256 bytes ./NCChatTitleView.m
7204 bytes ./NCMessageParameter.m
6526 bytes ./CCCertificate.m
6259 bytes ./NCIntentController.m
6108 bytes ./ReplyMessageView.m
6096 bytes ./NCRoomParticipants.m
5719 bytes ./NCAudioController.m
5535 bytes ./NCSignalingController.m
5369 bytes ./NCPushNotification.m
5153 bytes ./NCUserStatus.m
4965 bytes ./SystemMessageTableViewCell.m
4882 bytes ./NCNotification.m
4827 bytes ./AutoCompletionTableViewCell.m
4620 bytes ./ResultMultiSelectionTableViewController.m
4420 bytes ./NCKeyChainController.m
4241 bytes ./QuotedMessageView.m
4049 bytes ./DetailedOptionsSelectorTableViewController.m
3909 bytes ./SocketConnection.m
3739 bytes ./MapViewController.m
3704 bytes ./WSMessage.m
3676 bytes ./SearchTableViewController.m
3413 bytes ./NCUser.m
3412 bytes ./NCContact.m
3195 bytes ./ContactsTableViewCell.m
2617 bytes ./NCAvatarSessionManager.m
2530 bytes ./MessageBodyTextView.m
2465 bytes ./GeoLocationRichObject.m
1967 bytes ./ScreenCaptureController.m
1798 bytes ./VoiceMessageRecordingView.m
1722 bytes ./NCMessageFileParameter.m
1713 bytes ./NCMessageTextView.m
1651 bytes ./NCPoll.m
1642 bytes ./NCPushNotificationsUtils.m
1571 bytes ./NCNavigationController.m
1556 bytes ./NCUserDefaults.m
1556 bytes ./BarButtonItemWithActivity.m
1503 bytes ./AvatarBackgroundImageView.m
1365 bytes ./NotificationCenterNotifications.m
1362 bytes ./NCScreensharingController.m
1274 bytes ./PlaceholderView.m
1139 bytes ./HeaderWithButton.m
811 bytes ./ABContact.m
585 bytes ./DateHeaderView.m
518 bytes ./NCMessageLocationParameter.m
506 bytes ./NCDeckCardParameter.m
447 bytes ./NCChatReaction.m
335 bytes ./main.m
322 bytes ./FederatedCapabilities.m
314 bytes ./ServerCapabilities.m
255 bytes ./TalkCapabilities.m
242 bytes ./TalkAccount.m
187 bytes ./NCChatBlock.m
```