Add an option to allow enabling/disabling build isolation

[atugushev]

Closes #721.

Changelog-friendly one-liner: Add an option to allow enabling/disabling build isolation

Contributor checklist

• Provided the tests for the changes.
• Requested a review from another contributor.
• Gave a clear one-line description in the PR (that the maintainers can add to CHANGELOG.md on release).
• Assign the PR to an existing or new milestone for the target version (following Semantic Versioning).

[blueyed]

Test should be enhanced.

[codecov]

Codecov Report

Merging #758 into master will increase coverage by 0.03%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #758      +/-   ##
==========================================
+ Coverage   91.94%   91.97%   +0.03%     
==========================================
  Files          35       35              
  Lines        2296     2305       +9     
  Branches      306      307       +1     
==========================================
+ Hits         2111     2120       +9     
  Misses        153      153              
  Partials       32       32

Impacted Files	Coverage Δ
piptools/repositories/pypi.py	89.15% <100%> (+0.06%)	⬆️
tests/test_cli_compile.py	100% <100%> (ø)	⬆️
piptools/scripts/compile.py	100% <100%> (ø)	⬆️

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[jkp]

Will this get merged?

[atugushev]

pip-tools v3.5.0 is released