chore(cli): --save-dev with --save-prod implies as dev

[await-ovo]

Behavior consistent with pnpm when --save-dev with --save-prod:

pnpm add some-pkg --save-prod --save-dev will only be installed as devDependencies.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.64%. Comparing base (c62a631) to head (75315ef).
⚠️ Report is 6 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #216      +/-   ##
==========================================
- Coverage   92.65%   92.64%   -0.02%     
==========================================
  Files          57       57              
  Lines        2847     2856       +9     
==========================================
+ Hits         2638     2646       +8     
- Misses        209      210       +1     

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[KSXGitHub]

I think pnpm is in the wrong in this case, but no one cares enough to fix it yet.

What's your opinion, @zkochan?

[zkochan]

How would you expect it to work at all? I would throw an error in this case.