Migrate block/unblock user endpoints to generated models

[gpunto]

Goal

Migrate the /users/block and /users/unblock endpoints to generated request/response models. Part of the incremental OpenAPI model migration: generated models keep their generated package (io.getstream.chat.android.network.models) as internal classes inside the client module, one endpoint at a time.

Closes AND-1293

Implementation

• Add generated BlockUsersRequest, BlockUsersResponse, UnblockUsersRequest, UnblockUsersResponse and delete the four hand-written DTOs.
• Point UserApi, MoshiChatApi, and the toDomain() mapper at the generated types (real names, no import aliases), updating field access to the generated camelCase names.
• queryBlockedUsers is left untouched (independent). Also fixes a pre-existing copy-paste where the unblock test argument used the block response type.

Testing

• Project-wide spotlessApply, apiDump (no API drift), lint, detekt, and testDebugUnitTest all pass.
• Verified on device: block a real user, confirm the id round-trips through request -> response (UserBlock), then unblock succeeds.

[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	11.20 MB	0.00 MB	🟢
stream-chat-android-compose	12.66 MB	12.66 MB	0.00 MB	🟢