[NEW] message deletion syncing

[AdamUncao]

@RocketChat/ios

Added support for /api/v1/chat.getDeletedMessages in order to sync deleted messages
RoomDeletedMessagesRequest.swift taken from luismachado PR #2617

Closes #2208

[CLAassistant]

All committers have signed the CLA.

[codecov]

Codecov Report

Merging #2738 into develop will decrease coverage by 0.05%.
The diff coverage is 7.4%.

@@             Coverage Diff             @@
##           develop    #2738      +/-   ##
===========================================
- Coverage    45.07%   45.01%   -0.06%     
===========================================
  Files          626      627       +1     
  Lines        28926    28980      +54     
===========================================
+ Hits         13039    13046       +7     
- Misses       15887    15934      +47

Impacted Files	Coverage Δ
Rocket.Chat/Models/Subscription/Subscription.swift	51.02% <ø> (+2.04%)	⬆️
...API/Requests/Room/RoomDeletedMessagesRequest.swift	0% <0%> (ø)
...Chat/Controllers/Chat/MessagesViewController.swift	1.37% <0%> (-0.01%)	⬇️
Rocket.Chat/API/Clients/SubscriptionsClient.swift	59.01% <0%> (-7.04%)	⬇️
...cket.Chat/Controllers/Chat/MessagesViewModel.swift	38.42% <66.66%> (+0.37%)	⬆️
...s/Controllers/NotificationViewControllerSpec.swift	84.61% <0%> (ø)	⬆️
...lers/Notification/NotificationViewController.swift	54.87% <0%> (ø)	⬆️
...rs/Notification/TopTransparentViewController.swift	100% <0%> (+33.33%)	⬆️

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