feat: vux loader plugins支持webpack5

[qiudaoermu]

Please makes sure the items are checked before submitting your PR, thank you!

• [ ] Rebase before creating a PR to keep commit history clear.
• [ ] Only One commit
• [ ] No eslint errors

[qiudaoermu]

大佬，给合一下

[Evans-Cai]

这个项目还有人维护吗，感觉作者也不知道看了，而且也没有代管理人员

[eJayYoung]

@vux/loader v2.1.2 @qiudaoermu