Optimize the build process and Manage environment variables using.env

[lepen-yang]

What is the purpose of the change

Optimize the build process, now use start.js script to start the build or webpack service, previously added environment variables in npm script, now use.env.* to manage environment variables in different build environments, You can put environment variables that you do not want to submit to github into the.env.* file (such as the address of the public server) to optimize the output of the webpack build, other details please review code

优化构建流程，现在使用 start.js 脚本来启动构建或webpack服务，之前在 npm script 脚本中添加环境变量，现在使用 .env.* 来管理 不同构建环境下的环境变量，可以将不希望提交到github的环境变量放到.env.*文件中（比如公网服务器的地址），优化 webpack 构建时的输出，其他细节请review code

dev 命令下

build 命令下

可以 clone：https://github.com/15100399015/SolidUI/tree/dev ，来验证代码效果

Brief change log

Checklist

• I have read the Contributing Guidelines on pull requests.
• I have explained the need for this PR and the problem it solves
• I have explained the changes or the new features added to this PR
• I have added tests corresponding to this change
• I have updated the documentation to reflect this change
• I have verified that this change is backward compatible
• If this is a code change: I have written unit tests to fully verify the new behavior.

[nutsjian]

well done