fix: graceful shutdown on watch/cache

[evenstensberg]

What kind of change does this PR introduce?

#3075

Did you add tests for your changes? TBD

If relevant, did you update the documentation? TBD Summary

Does this PR introduce a breaking change?

No

Other information

Need to add tests.

[codecov[bot]]

Codecov Report

:white_check_mark: All modified and coverable lines are covered by tests. :white_check_mark: Project coverage is 89.70%. Comparing base (f407b24) to head (f29d6e8). :warning: Report is 41 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4546      +/-   ##
==========================================
+ Coverage   89.68%   89.70%   +0.02%     
==========================================
  Files           9        9              
  Lines        1396     1399       +3     
  Branches      445      447       +2     
==========================================
+ Hits         1252     1255       +3     
  Misses        144      144              

Files with missing lines	Coverage Δ
packages/webpack-cli/src/webpack-cli.ts	90.70% <100.00%> (+0.02%)	:arrow_up:

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[evenstensberg]

Still wip, need to send a sigterm signal whenever.

[evenstensberg]

@alexander-akait PTAL before new release.