Provide a "class" row factory

**Is your feature request related to a problem? Please describe.**
Currently, comdb2 module provides dict and namedtuple factories. It would also be nice to provide a "class" row factory which would allow rows returned as client-defined dataclasses, pydantic models, etc.

**Describe the solution you'd like**
See a similar concept in psycopg's `class_row` factory: https://www.psycopg.org/psycopg3/docs/api/rows.html#psycopg.rows.class_row
This also allows nice static type checking: https://www.psycopg.org/psycopg3/docs/advanced/typing.html#example-returning-records-as-pydantic-models

先在儲存庫中找出現有的 dict 和 namedtuple 列工廠，然後將它們的介面與 psycopg 的 class_row 文件進行比較。這項變更應支援將用戶端定義的 dataclasses 和 pydantic 模型作為列結果，並提供類似連結範例的靜態型別。查看已關閉的 pull request #57，以了解先前實作的背景與預期行為。

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