fix: 修复 configWebpack 无法修改 plugins 里配置的问题

[noyobo]

// remax.config.js
{
  plugins: [require('@remax/plugin-less')],
  configWebpack({config }){
    // 此时无法修改 plugin 的配置
  }
}

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[codecov]

Codecov Report

Merging #1356 into master will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #1356   +/-   ##
=======================================
  Coverage   95.36%   95.36%           
=======================================
  Files         350      350           
  Lines        3778     3778           
  Branches      543      543           
=======================================
  Hits         3603     3603           
  Misses        172      172           
  Partials        3        3           

Impacted Files	Coverage Δ
...ackages/remax-cli/src/build/webpack/config.mini.ts	100.00% <100.00%> (ø)
packages/remax-cli/src/build/webpack/config.web.ts	95.65% <100.00%> (ø)

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