fix(jest generator): accurate test script in windows platform

[zhoudailin]

生成器生成的test script在windows上不能直接使用，判断当前平台生成不同的script

[vercel]

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1 Ignored Deployment

Name	Status	Preview	Updated
umi	⬜️ Ignored (Inspect)		Dec 23, 2022 at 7:10AM (UTC)

[codecov]

Codecov Report

Base: 29.88% // Head: 29.88% // No change to project coverage 👍

Coverage data is based on head (be74ee1) compared to base (a877616).
Patch coverage: 0.00% of modified lines in pull request are covered.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #10133   +/-   ##
=======================================
  Coverage   29.88%   29.88%           
=======================================
  Files         432      432           
  Lines       12407    12407           
  Branches     2973     2973           
=======================================
  Hits         3708     3708           
  Misses       8133     8133           
  Partials      566      566           

Impacted Files	Coverage Δ
...ackages/preset-umi/src/commands/generators/jest.ts	0.00% <0.00%> (ø)

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[fz6m]

依赖里加一个 cross-env ，然后用 cross-env 指定环境变量

[zhoudailin]

依赖里加一个 cross-env ，然后用 cross-env 指定环境变量

用cross-env肯定更好，但是需要引入cross-env，我看贡献的指南里面推荐我们别去改依赖，我也没注意是不是已经引入了cross-env，所以判断了下平台

[fz6m]

这个行为会添加很多 jest 的依赖的，我理解 “不改依赖” 指的是 umi 框架的依赖，这个功能是用户主动添加的行为，本来就会操作用户的依赖的。

[zhoudailin]

这个行为会添加很多 jest 的依赖的，我理解 “不改依赖” 指的是 umi 框架的依赖，这个功能是用户主动添加的行为，本来就会操作用户的依赖的。

好的，那我等会去引入cross-env来处理