fix: SSR not supports node 14.x optional chaining

[ycjcl868]

ref: webpack/webpack#10227
Close #4873

修复 SSR 不支持 Node 14 默认开启的 Optional Chaining

Checklist

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

Description of change

• any feature?
• close https://github.com/umijs/umi/ISSUE_URL

[codecov]

Codecov Report

Merging #4980 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #4980   +/-   ##
=======================================
  Coverage   83.03%   83.03%           
=======================================
  Files         153      153           
  Lines        3372     3372           
  Branches      883      897   +14     
=======================================
  Hits         2800     2800           
+ Misses        565      564    -1     
- Partials        7        8    +1     

Impacted Files	Coverage Δ
packages/babel-preset-umi/src/index.ts	85.71% <ø> (ø)
packages/core/src/Config/Config.ts	61.78% <0.00%> (ø)

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