WebSecurityConfigurerAdapter is deprecated

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### This issue is for a: (mark with an `x`)
```
- [ ] bug report -> please search issues before submitting
- [ ] feature request
- [x] documentation issue or request
- [ ] regression (a behavior that used to work and stopped in a new release)
```

### Minimal steps to reproduce
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### Any log messages given by the failure
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### Expected/desired behavior
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### OS and Version?
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### Versions
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### Mention any other details that might be useful
WebSecurityConfigurerAdapter (and therefore AadWebsecurityConfigurerAdapter) is deprecated. Vast majority of current configuration examples for spring boot are outdated and make it difficult to reconcile with latest spring boot version. Please update here as well as on the Microsoft dev guides.
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リポジトリの現在の Spring Boot 設定例と参照されている Microsoft の開発者向けガイドを確認し、非推奨の WebSecurityConfigurerAdapter に関するガイダンスと比較します。対象となる例とガイドが最新の設定ガイダンスを使用し、非推奨の adapter に依存しなくなれば完了です。

索引モデルが issue の本文から書いたものです。