Introduce datatable.unique.names policy for duplicate handling in setnames() #4044

[venom1204]

Closes #4044

Hi @ben-schwen,

Apologies for opening a new PR—there was an issue with the previous one. I’ve incorporated the requested changes, while keeping the rest unchanged.

Kindly review it when you have the time. Also, sorry for the delay; I was occupied with other commitments.

Thank you!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.04%. Comparing base (7db13b9) to head (471ab20).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #7674   +/-   ##
=======================================
  Coverage   99.04%   99.04%           
=======================================
  Files          87       87           
  Lines       17031    17049   +18     
=======================================
+ Hits        16868    16886   +18     
  Misses        163      163           

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[github-actions]

No obvious timing issues in HEAD=issue4044

Generated via commit 471ab20

Download link for the artifact containing the test results: ↓ atime-results.zip

Task	Duration
R setup and installing dependencies	2 minutes and 53 seconds
Installing different package versions	23 seconds
Running and plotting the test cases	4 minutes and 3 seconds