PinnedMessageList Compose

[VelikovPetar]

🎯 Goal

The goal of the PR is to introduce a compose implementation of the PinnedMessageList component (which already exists in the XML SDK)

🛠 Implementation details

1. Extracted the business logic from the already existing PinnedMessageListViewModel into a PinnedMessageListController.
2. Use the PinnedMessageListController in the already existing PinnedMessageListViewModel(xml) and in the new PinnedMessageListViewModel(compose).
3. Implement new PinnedMessageList composable component which accepts the PinnedMessageListViewModel.
4. Create new MessagePreviewItem which serves as a base for the PinnedMessageItem composable -> similar to how this is done in the XML (MessagePreviewView used for: SearchResults, PinnedMessages and Mentions). In the future, we can use the same item to also handle the Mentions when we implement them in compose.
5. Extend the MessagePreviewFormatter interface with a new method: formatMessageTitle - this formatter can now be used to format both the title and the body of the MessagePreviewItem

Additional: Implement basic ChannelInfoActivity, GroupChannelInfoActivity and PinnedMessagesActivity in the compose sample so that the 'pinned messages' composable can be easily tested. (used the XML sample as a UI reference)

🎨 UI Changes

PinnedMessageList

XML	Compose
showcase-empty-xml-4.mp4	showcase-empty-compose.mp4
showcase-error-xml.mp4	showcase-error-compose.mp4
showcase-pagination-xml.mp4	showcase-pagination-compose.mp4

Compose sample app

ChannelInfoActivity	GroupChannelInfoActivity

🧪 Testing

1. Open the compose sample app
2. Open a conversation with pinned messages
3. Click on the header title to open the channel info
4. Click on the "Pinned messages" item

☑️Contributor Checklist

General

• I have signed the Stream CLA (required)
• Assigned a person / code owner group (required)
• Thread with the PR link started in a respective Slack channel (#android-chat-core or #android-chat-ui) (required)
• PR targets the develop branch
• PR is linked to the GitHub issue it resolves

Code & documentation

• Changelog is updated with client-facing changes
• New code is covered by unit tests
• Comparison screenshots added for visual changes
• Affected documentation updated (KDocs, docusaurus, tutorial)

☑️Reviewer Checklist

• UI Components sample runs & works
• Compose sample runs & works
• UI Changes correct (before & after images)
• Bugs validated (bugfixes)
• New feature tested and works
• Release notes and docs clearly describe changes
• All code we touched has new or updated KDocs

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