feat: install required packages for loading command automatically

[snitin315]

What kind of change does this PR introduce? feature

Did you add tests for your changes? WIP in tests If relevant, did you update the documentation? NA Summary

https://github.com/webpack/webpack-cli/pull/2809#issuecomment-870755830

Does this PR introduce a breaking change? No

Other information No

[snitin315]

smoke tests passing locally 😞.

[snitin315]

Yes, we should do it for all.

[codecov[bot]]

Codecov Report

Merging #2815 (88d24d9) into master (3e2bb73) will decrease coverage by 0.08%. The diff coverage is 80.00%.

@@            Coverage Diff             @@
##           master    #2815      +/-   ##
==========================================
- Coverage   95.01%   94.93%   -0.09%     
==========================================
  Files          31       32       +1     
  Lines        1706     1717      +11     
  Branches      498      500       +2     
==========================================
+ Hits         1621     1630       +9     
- Misses         85       87       +2     

Impacted Files	Coverage Δ
...kages/webpack-cli/lib/utils/prompt-installation.js	76.92% <71.42%> (+1.92%)	:arrow_up:
packages/webpack-cli/lib/webpack-cli.js	96.87% <100.00%> (+<0.01%)	:arrow_up:
packages/webpack-cli/lib/utils/run-command.js	75.00% <0.00%> (ø)

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[snitin315]

/cc @webpack/cli-team, Can someone check it locally on Linux/windows, all tests are passing on my macOS. (Missing prettier smoketests specially)

[alexander-akait]

@snitin315 Do we need this, I just checked and we don't ask about installation when I use webpack init