feat: add vertical tabs panel position toggle

[oz-for-oss]

Closes #9825

Summary

• Add a Left/Right Position segmented control to the vertical tabs View options popup.
• Reuse the existing header toolbar chip selection to move the vertical tabs panel between sides.
• Track the new position option in vertical tabs telemetry and add focused unit coverage for the selection helper/action classification.

Validation

• cargo fmt --manifest-path /workspace/warp/Cargo.toml --all
• CARGO_BUILD_JOBS=1 cargo check -p warp --lib
• CARGO_BUILD_JOBS=1 cargo clippy -p warp --lib -- -D warnings
• Attempted CARGO_BUILD_JOBS=1 cargo test -p warp --lib vertical_tabs_panel_position_change_does_not_save_workspace_state; the warp lib test build was killed by SIGKILL before tests could run in this sandbox.

Notes

• No issue-specific spec files were present, so none were updated.
• A demo screenshot was requested in issue discussion, but this automated branch handoff did not create one.