chore: control customized runtime by stage

[CJY0208]

Checklist

• npm test passes
• tests are included
• documentation is changed or added
• commit message follows commit guidelines

Description of change

• No any feature

Referrence issue

alitajs/umi-plugin-keep-alive#16

[codecov]

Codecov Report

Merging #5055 into master will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #5055      +/-   ##
==========================================
+ Coverage   82.84%   82.86%   +0.02%     
==========================================
  Files         153      153              
  Lines        3381     3385       +4     
  Branches      888      889       +1     
==========================================
+ Hits         2801     2805       +4     
  Misses        573      573              
  Partials        7        7              

Impacted Files	Coverage Δ
...-built-in/src/plugins/generateFiles/core/plugin.ts	100.00% <100.00%> (ø)

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[CJY0208]

referrence issue: alitajs/umi-plugin-keep-alive#16

[CJY0208]

存在一定风险，以前自定义运行时必然最末尾

但目前加入了 stage，尽可能给了最小的 stage

但依然可能让某些 runtime 依赖于 stage 的 plugin 的顺序出错

[sorrycc]

不敢合，感觉会有 break change。

[CJY0208]

理解，我再看看我遇到的问题是否有其他解法

目前看到的变化是自定义运行时将会接受 stage 控制，影响 src/.umi/core/plugin.ts 中 自定义运行时的放置顺序

如果是 stage 顺序上的 break change，排查官方 plugin 对 addRuntimePlugin stage 的使用大概可以控制住风险范围

但没办法保证非官方 plugin 是否受影响

其他的 break change 就不太清楚了

[sorrycc]

先 Close 了，有需要再开。