Add focus request handling to MessageComposer for improved user exper…

[Sagar0-0]

🎯 Goal

Introduce a mechanism to programmatically request focus on the message input field when a MessageAction is triggered, improving UX in actions like replying, editing, or thread replies.

🛠 Implementation details

• Introduced a focusRequestFlow in MessageComposerViewModel to emit one-shot focus events.
• Collected this flow in the default input = MessageComposer composable using LaunchedEffect to request focus and show the keyboard.
• Used FocusRequester and LocalSoftwareKeyboardController to programmatically focus and open the keyboard.
• Applied the FocusRequester to the message input using a Modifier.

This can be further improved by passing a focusRequester as a parameter in the input (along with the state), but that would require changes in many places, which is why I avoided it and added the mechanism only to the default input.

Let me know if there are better places to add this in the Compose code. I believe it's better to provide an option to pass/access for Modifier or FocusRequester for Message Input.

🎨 UI Changes

Add relevant videos

Before	After
Record_2025-06-10-19-33-08.mp4	Record_2025-06-10-19-24-27.mp4

🧪 Testing

• Manually verified that when a MessageAction like Reply, Edit, or ThreadReply is triggered, the message input gains focus and the keyboard opens.
• Tested in both default and custom input configurations.

☑️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 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

🎉 GIF

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[github-actions]

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