Migrate partial message update and reminder request bodies to generated models

[gpunto]

Goal

Migrate the partial-message-update and reminder request bodies (partialUpdateMessage, createReminder, updateReminder) to the generated UpdateMessagePartialRequest, CreateReminderRequest, and UpdateReminderRequest network models.

Part of AND-1291

Stacked on #6607 (migrate/poll-write-requests) — this PR's base is that branch, so the diff shown is only the message/reminder changes. Merge #6607 first; GitHub will then retarget this PR to develop.

Implementation

• Add generated UpdateMessagePartialRequest, CreateReminderRequest, UpdateReminderRequest; remove the hand-written PartialUpdateMessageRequest and ReminderRequest.
• MoshiChatApi mappers and the message/reminder @Body types retyped to the generated models.

Testing

• New MessageAndReminderRequestAdapterTest locks the wire shape, including the remind_at date format and the set/skip_enrich_url/skip_push fields.
• spotlessApply, apiDump (no public-API change), detekt, and the full client testDebugUnitTest suite pass.

[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	5.96 MB	5.95 MB	-0.01 MB	🚀
stream-chat-android-ui-components	11.22 MB	11.24 MB	0.02 MB	🟢
stream-chat-android-compose	12.71 MB	12.72 MB	0.01 MB	🟢

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud