[CIS-254] Implement methods for working with invites

[dmigach]

Add methods for inviting a member, and for accepting/rejecting the invite.

channelController.inviteMembers(userIds: ["luke_skywalker", "leia_organa"]) { error in ... }

channelController.acceptInvite(message: "Hi everyone!") { error in ... }

channelController.rejectInvite() { error in ... }

After this change will have been merged, customers will be able to call invite/acceptInvite/rejectInvite endpoints, but they won't be able to react to events. For this to work we need changes from Pavel that introduce a mechanism for propagating events to customers' code

[Stream-iOS-Bot]

	1 Warning
⚠️	Big PR

Generated by 🚫 Danger

[codecov-commenter]

Codecov Report

Merging #1276 (2f7ce54) into main (b3ebf0f) will decrease coverage by 0.29%.
The diff coverage is 76.92%.

@@            Coverage Diff             @@
##             main    #1276      +/-   ##
==========================================
- Coverage   91.42%   91.12%   -0.30%     
==========================================
  Files         219      219              
  Lines        9488     9576      +88     
==========================================
+ Hits         8674     8726      +52     
- Misses        814      850      +36     

Flag	Coverage Δ
llc-tests	91.12% <76.92%> (-0.14%)	⬇️
llc-tests-ios12	91.12% <76.92%> (+2.98%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...t/APIClient/Endpoints/Payloads/MemberPayload.swift	100.00% <ø> (ø)
Sources/StreamChat/Query/ChannelQuery.swift	100.00% <ø> (ø)
...at/WebSocketClient/Events/NotificationEvents.swift	64.28% <0.00%> (-25.72%)	⬇️
.../StreamChat/WebSocketClient/Events/EventType.swift	92.30% <50.00%> (-7.70%)	⬇️
...trollers/ChannelController/ChannelController.swift	92.23% <75.00%> (-0.87%)	⬇️
...eamChat/APIClient/Endpoints/ChannelEndpoints.swift	100.00% <100.00%> (ø)
...rces/StreamChat/Database/DTOs/MemberModelDTO.swift	100.00% <100.00%> (ø)
Sources/StreamChat/Workers/ChannelUpdater.swift	98.11% <100.00%> (+0.17%)	⬆️
...ocketClient/Engine/StarscreamWebSocketEngine.swift	0.00% <0.00%> (-30.96%)	⬇️
.../Utils/InternetConnection/InternetConnection.swift	54.05% <0.00%> (-0.91%)	⬇️
... and 1 more

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[evsaev]

CHANGELOG and LGTM 👍

[evsaev]

Looks good, thanks 👍