Add qblike_3 example. (#42)

Add example that demonstrates the typing of a SQL-alchemy like query
builder, allowing selects on tables and fields.

Single table queries such as `session.execute(select(User))` will return
a list of
```py
    class Select[User, tuple[...]]:
        id: int
        name: str
        email: str
        age: int | None
        active: bool
        posts: list[Post]
```

Multi table queries such as `session.execute(select(User.name,
Post.content))` will return a list of
```py
    class QueryRow[...]:
        User: Select[User, tuple[...]]]:
        Post: Select[Post, tuple[...]]]:
```

where
```py
    class Select[User, tuple[...]]:
        name: str

    class Select[Post, tuple[...]]:
        content: str
```

Author: dnwpark