feat: bundle webpack

[xiaohuoni]

---

Please don't delete this checklist! Before submitting the PR, please make sure you do the following:

• It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC. Support bundle with webpack #49
• This message body should clearly illustrate what problems it solves.
• Ideally, include a test that fails without this PR but passes with it.

Tests

• Run the tests and other checks with pnpm ci

规则是用户自己安装 @umijs/bundler-webpack 触发 doctor 报错 @sorrycc

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Edits

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[changeset-bot]

🦋 Changeset detected

Latest commit: 6c455f8

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[sorrycc]

doctor 到问题不大，主要是少了 dev，之前也尝试加过，但发现 bundler-webpack 这个包接 dev 比较麻烦，于是就先放着了。

[xiaohuoni]

我看需求里面写，只要实现 build 我以为，只要 build 阶段切换 webpack。
那我再跑一跑