Migrate channel config request bodies to generated models

[gpunto]

Goal

Migrate the channel-config request bodies (hideChannel, muteChannel/unmuteChannel, updateChannelPartial) to generated models. Part of the incremental OpenAPI model migration.

Part of AND-1291

Implementation

• Add generated internal HideChannelRequest, MuteChannelRequest, UpdateChannelPartialRequest in network.models; delete the hand-written ones. Repoint ChannelApi, ModerationApi, MoshiChatApi, and tests.
• MuteChannelRequest: the field is now channelCids: List<String> (was channel_cid: String); both muteChannel and unmuteChannel pass listOf("$type:$id"). Wire payload verified unchanged in behaviour on device.
• UpdateChannelPartialRequest: generated field order is (unset, set), so the call site now uses named args (set = set, unset = unset).
• HideChannelRequest: clearHistory is now Boolean? (was Boolean); the call passes it positionally, no logic change.

Testing

• Project-wide spotlessApply, apiDump (no API drift), detekt, and testDebugUnitTest all pass.
• Verified on device: hideChannel/showChannel -> 200, muteChannel/unmuteChannel -> 200, and updateChannelPartial -> 200 with a custom-field (extraData) round-trip confirmed (sentinel set then unset).

[github-actions]

PR checklist ✅

All required conditions are satisfied:

• Title length is OK (or ignored by label).
• At least one pr: label exists.
• Sections ### Goal, ### Implementation, and ### Testing are filled, or the PR is bot-authored.
• An issue is linked (Linear ticket or GitHub issue), or the PR is bot-authored.

🎉 Great job! This PR is ready for review.

[github-actions]

SDK Size Comparison 📏

SDK	Before	After	Difference	Status
stream-chat-android-client	5.93 MB	5.93 MB	0.00 MB	🟢
stream-chat-android-ui-components	11.20 MB	11.19 MB	-0.00 MB	🚀
stream-chat-android-compose	12.66 MB	12.67 MB	0.00 MB	🟢

[sonarqubecloud]

Quality Gate failed

Failed conditions
61.5% Coverage on New Code (required ≥ 80%)

See analysis details on SonarQube Cloud