Also migrate dynamic Oxlint & Oxfmt configurations if they exist

### Description

From what I can see it seems like `oxlint.config.ts` and `oxfmt.config.ts` doesn't have a migration flow yet. This seems like a bit of low-hanging fruit.

### Suggested solution

Probably replicate how Vitest & tsdown are migrated.

### Alternative

Manual migration, but we already have their `.ox*rc.json(c)` versions migratable, why not these ones too?

### Additional context

_No response_

### Validations

- [x] Read the [Contributing Guidelines](https://github.com/voidzero-dev/vite-plus/blob/main/CONTRIBUTING.md).
- [x] Confirm this request is for Vite+ itself and not for Vite, Vitest, tsdown, Rolldown, or Oxc.
- [x] Check that there isn't already an issue requesting the same feature.

Vitest と tsdown の既存の移行フローを確認し、.ox*rc.json(c) 設定の移行処理と比較します。これらのファイルが存在する場合は、oxlint.config.ts と oxfmt.config.ts に同等の処理を追加し、両方の動的設定が正しく移行されることを検証します。

索引モデルが issue の本文から書いたものです。