[Discussion] Remove use of `dialect_of` macro

What was the purpose of the current `Dialect`?
The `dialect_of` macro makes it difficult to modify your code whenever you add support for Dialect.
And besides the identifier support of Dialect, it seems that it can also support query (Expr).

But... if you have other intentions for macros
Since there is a problem, I would like to discuss it with the maintainers.

阅读当前的 `Dialect` 定义和 `dialect_of` 宏的实现，重点关注讨论中提到的 identifier 和 `Expr` 支持。查看维护者的评论，以确定该宏预期承担的角色。要视为完成，需要达成一致的设计和范围，而 issue 中尚未确定这些内容。

由索引模型根据 Issue 内容生成。