[ML 0.5/MVI.02.6] Implement Outbox Integration and Backend Enqueueing

Description

Implement the specific logic within the DeleteMessages flow to handle messages located in the Outbox and finalize the backend command orchestration.

Goal

Ensure data integrity for pending transmissions and ensure the server state accurately mirrors local deletions according to the account's DeletePolicy.

Acceptance Criteria

• Detects Outbox folder matches and emits RequestCopyLocalTrashMessageToRemoteTrash when required.
• Correctly enqueues Delete, Move, or MarkAsRead commands based on Backend capabilities and the DeletePolicy.
• Testing: Unit tests verifying that the correct Enqueue commands are emitted when the Outbox or specific delete policies are involved.