Move GenericServerObject to warp_server_client.

[vorporeal]

Description

Moves GenericServerObject into warp_server_client so the server-response representation can be reused outside the app crate.

This is the next extraction layer after the low-level type move: server-backed object containers are now portable, while app-specific model behavior remains implemented in warp. The new upstream server_object module owns the generic server container and supporting traits/status types, and app code adapts by implementing the minimal upstream model trait where needed.

This reduces the amount of app-only infrastructure that future server-client code has to depend on before GenericCloudObject can move upstream.

Testing

Validated on the stack tip after Phase 3:

• cargo fmt --manifest-path /Users/david/src/warp/Cargo.toml --all
• cargo check --manifest-path /Users/david/src/warp/Cargo.toml -p warp_server_client
• cargo check --manifest-path /Users/david/src/warp/Cargo.toml -p warp
• cargo check --manifest-path /Users/david/src/warp/Cargo.toml -p warp --tests
• git --no-pager diff --check

Co-Authored-By: Oz oz-agent@warp.dev

[vorporeal]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• Move GenericStringModel to warp_server_client. #11117
• Move GenericCloudObject to warp_server_client. #11115
• Move GenericServerObject to warp_server_client. #11114 👈 (View in Graphite)
• Move some types to the warp_server_client crate. #11113
• Delete unused new_from_server_update function. #11112
• master

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