Always wrap statement in a named struct

In [GreptimeDB](https://github.com/GreptimeTeam/greptimedb/blob/v0.7.1/src/sql/src/statements/delete.rs), we write code like:

```rust
#[derive(Debug, Clone, PartialEq, Eq, Visit, VisitMut)]
pub struct Delete {
// Can only be sqlparser::ast::Statement::Delete variant
pub inner: Statement,
}
```

It's because in sqlparser-rs, these statement variants are unnamed struct:

```rust
Delete {
/// Multi tables delete are supported in mysql
tables: Vec,
/// FROM
from: Vec,
/// USING (Snowflake, Postgres, MySQL)
using: Option>,
/// WHERE
selection: Option,
/// RETURNING
returning: Option>,
},
```

I wonder if we can always wrap statement in a named struct so that downstream software can reuse the AST and impls (like for Display) more smoothly.

I don't know if it's a breaking change or we're generally OK with this.

Ref - https://github.com/GreptimeTeam/greptimedb/issues/3646

Comece revisando as definições de statements no sqlparser AST e o wrapper downstream mostrado em src/sql/src/statements/delete.rs do GreptimeDB. Verifique como o código downstream implementa ou consome Display e outras traits do AST e, em seguida, determine o impacto de compatibilidade de envolver cada variante de statement. Considera-se concluído quando houver um design documentado ou um plano de implementação aceito que trate das questões de reutilização e breaking changes.

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