[CIS-1491] Add custom modal transition for message list

[nuno-vieira]

🔗 Issue Link

CIS-1491
#1307

🎯 Goal

Introduces a custom modal transition to workaround the inverted table view on the message list. This custom transition should be used if you as a customer need to present the ChatChannelVC in a modal.

Usage:

// Make sure to have a reference to the delegate or it will be instantly deallocated.
let streamModalTransitioningDelegate = StreamModalTransitioningDelegate()

func showChannelVC() {
    let vc = ChatChannelVC()
    vc.channelController = client.channelController(for: cid)
    let navVC = UINavigationController(rootViewController: vc)
    navVC.transitioningDelegate = streamModalTransitioningDelegate
    navVC.modalPresentationStyle = .custom
    navigationController?.present(navVC, animated: true, completion: nil)
}

🛠 Implementation

Adds a new StreamModalTransitioningDelegate that mimics the native's modal transition.

🎨 Changes

ModalTransition.mp4

🧪 Testing

Check the video on how to test this in the demo app.

☑️ Checklist

• I have signed the Stream CLA (required)
• This change follows zero ⚠️ policy (required)
• Changelog is updated with client-facing changes
• New code is covered by unit tests
• Affected documentation updated (docusaurus, tutorial, CMS (task created)

[codecov]

Codecov Report

Merging #1760 (f9ca5b5) into develop (8bcce18) will decrease coverage by 0.01%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop    #1760      +/-   ##
===========================================
- Coverage    85.39%   85.37%   -0.02%     
===========================================
  Files          234      234              
  Lines        11247    11247              
===========================================
- Hits          9604     9602       -2     
- Misses        1643     1645       +2     

Flag	Coverage Δ
llc-tests	85.37% <ø> (-0.02%)	⬇️

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

Impacted Files	Coverage Δ
Sources/StreamChat/Utils/Logger/Logger.swift	56.28% <0.00%> (-1.80%)	⬇️
Sources/StreamChat/ChatClient.swift	91.42% <0.00%> (+0.23%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 8bcce18...f9ca5b5. Read the comment docs.

[bielikb]

I left couple of more comments here

[pbendersky]

We are trying to present the chat in a modal using UISheetPresentationController with detents, so the chat doesn't take over the entire screen.
Do you plan to support this scenario? Setting the presentation mode to .custom doesn't play nice with it based on our tests.