[CLNP-6807] feat: add support for custom FlatList component in message list

[OnestarLee]

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For Internal Contributors

[CLNP-6807](https://sendbird.atlassian.net/browse/CLNP-6807)

Description Of Changes

Added flatListComponent to GroupChannelFragment to support customization

Types Of Changes

What types of changes does your code introduce to this project?
Put an x in the boxes that apply_

• Bugfix
• New feature
• Documentation (correction or otherwise)
• Cosmetics (whitespace, appearance (ex) Prettier)
• Build configuration
• Improvement (refactor code)
• Test

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 11.49%. Comparing base (16e793c) to head (4450d97).

Files with missing lines	Patch %	Lines
...react-native/src/components/ChatFlatList/index.tsx	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #242      +/-   ##
==========================================
- Coverage   11.49%   11.49%   -0.01%     
==========================================
  Files         358      358              
  Lines        8489     8490       +1     
  Branches     2394     2395       +1     
==========================================
  Hits          976      976              
- Misses       7438     7439       +1     
  Partials       75       75              

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[Copilot]

Pull Request Overview

This PR adds support for a custom FlatList component in the message list by introducing a new optional prop ("flatListComponent") and propagating it through the GroupChannelFragment, ChannelMessageList, and ChatFlatList components.

• Introduces "flatListComponent" prop in the GroupChannelFragment and corresponding TypeScript types.
• Updates ChatFlatList to use the provided custom FlatList component or fallback to the default internal component.
• Propagates the prop through ChannelMessageList to enable custom FlatList rendering.

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
packages/uikit-react-native/src/fragments/createGroupChannelFragment.tsx	Adds the "flatListComponent" prop and passes it to the message list.
packages/uikit-react-native/src/domain/groupChannel/types.ts	Updates types to include the optional "flatListComponent".
packages/uikit-react-native/src/components/ChatFlatList/index.tsx	Adjusts ChatFlatList to conditionally render the custom FlatList.
packages/uikit-react-native/src/components/ChannelMessageList/index.tsx	Passes the "flatListComponent" prop down to ChatFlatList.

[bang9]

lgtm!