Improve ioredis exports to optimize bundle size

[Romakita]

Context

To reduce bundle size and improve modularity, the IORedisStore should no longer be exported from the main index.ts of @tsed/ioredis. Instead, it should be exposed via a dedicated export path: @tsed/ioredis/cache.

Objective

Update the exports field of the @tsed/ioredis module so that:

• Consumers must import IORedisStore from @tsed/ioredis/cache instead of the package root.

Deliverables

Subtask 1: Prepare for Transition in Ts.ED v8

• Expose IORedisStore through the new export path: @tsed/ioredis/cache (TypeScript & JS).
• Deprecate the export from the main index.ts but keep it available for backward compatibility.
• Add deprecation warnings and update documentation to inform users about the new import path.

Subtask 2: Breaking Change in Ts.ED v9

• Remove IORedisStore export from the package root (index.ts).
• Ensure IORedisStore is only accessible via @tsed/ioredis/cache.
• Update documentation and migration guides to reflect the breaking change.

Acceptance Criteria

• IORedisStore is accessible via @tsed/ioredis/cache in v8 (with deprecation notice).
• IORedisStore is no longer accessible via the package root in v9.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[Romakita]

Last task is to update documentation and prepare v9 migration note

[Romakita]

Resolved by #3131