refactor: handle APP_ROOT scenario in getPkg.ts

[leftstick]

Checklist

• npm test passes
• tests are included
• commit message follows commit guidelines

Description of change

handle APP_ROOT scenario properly in getPkg.ts.

related to #4044

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[codecov]

Codecov Report

Merging #4056 into master will increase coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #4056      +/-   ##
==========================================
+ Coverage   83.90%   83.91%   +0.01%     
==========================================
  Files         128      128              
  Lines        2528     2530       +2     
  Branches      640      631       -9     
==========================================
+ Hits         2121     2123       +2     
- Misses        398      399       +1     
+ Partials        9        8       -1     

Impacted Files	Coverage Δ
packages/core/src/Config/Config.ts	60.97% <0.00%> (ø)

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[sorrycc]

为啥我觉得在入口那里把 getPkg(process.cwd()) 改成 getPkg(getCwd()) || getPkg(process.cwd()) （getCwd() 返回值复用下）就好了。。

[leftstick]

为啥我觉得在入口那里把 getPkg(process.cwd()) 改成 getPkg(getCwd()) || getPkg(process.cwd()) （getCwd() 返回值复用下）就好了。。

我试试啊，昨天写的时候记得复用getCwd有问题才改成这样的，但这会又想不起来了。。。。

[leftstick]

@sorrycc 想起来了，getCwd里在没有APP_ROOT的情况下，默认返回cwd的值，有个ut不改cwd是跑不过的。因为ut直接从umi的根目录下也能找到package.json，不符合ut的预期。ut我改了下，还是调整下cwd，afterEach之后再还原就好了