[Enh]: Time to update the SqlClient driver

## What?

The latest stable SqlClient is `7.0.0`.

DAB is using `5.2.3` which is 2 major versions behind.

## Why?

1. Leaner, modular architecture. 7.0 was rewritten to be more lightweight with reduced dependencies
2. Improved OpenIdConnect/Entra ID authentication support which will matter to MCP soon!
3. Enhanced connection resiliency and retry logic. Just makes it all better.
4. TDS 8.0 protocol support for stricter encryption
5. Performance improvements across connection pooling and query execution
6. Security patches accumulated over two major versions

## Potential risks

1. Major version bumps (5 → 6 → 7) typically include breaking changes in API surface, connection string behavior, and default encryption settings. It should be okay, but this will require some testing and research to be sure.
2. SqlClient 6.0+ changed default encryption to `Mandatory`, which might break connections, but we can account for it
3. DAB's codebase has a note reminding devs to update scripts/notice-generation.ps1 when changing this package, suggesting there are known downstream impacts

Microsoft.Data.SqlClient に対する DAB パッケージ参照を特定し、issue で下流の更新箇所として示されている scripts/notice-generation.ps1 を調査します。5.x-to-7.0 の breaking changes、特に暗号化と認証が必須となる動作について調査し、影響を受けるデータベース接続と既存のチェックを確認します。完了条件は、プロジェクトが SqlClient 7.0.0 を使用し、notice の生成が最新の状態で、互換性リスクに対処できていることです。

索引モデルが issue の本文から書いたものです。