Logging integration to capture all logged exceptions

**Is your feature request related to a problem? Please describe.**
Instrumenting an existing application can be cumbersome: All places with exception handling need to be extend in order to also forward the errors to APM using `client.capture_exception()`. However, most of the time such code paths are already well covered with `logger.exception(...)` or similar.

**Describe the solution you'd like**
The APM library should offer an opt-in feature to automatically forward all logged exceptions to APM. This could be an automatic feature similar to how HTTP libraries get instrumented.

**Describe alternatives you've considered**
The APM `logging.LoggingHandler` class offers such functionality. However the capturing is hereby bound to a specific output format. It cannot easily be used together with `structlog`

This feature request is inspired by the integration offered by Sentry https://docs.sentry.io/platforms/python/guides/logging/.

**Additional context**
n/a

まず既存の APM logging.LoggingHandler と client.capture_exception() のエントリーポイントを読み、要求された動作を structlog の使用方法と比較します。特定の出力形式に依存せず、opt-in の統合によって記録された例外を APM に転送でき、サポートされる logging パスと設定が文書化されていれば完了です。

索引モデルが issue の本文から書いたものです。