net: recognize bare IPv6 loopback addresses in isLoopback

[watilde]

isLoopback() only matched bracket-wrapped IPv6 loopback addresses ([::1], [0:0:0:0:0:0:0:1]), but not the bare forms (::1, 0:0:0:0:0:0:0:1) that can appear when callers strip the brackets before passing the host string.

This change adds the two bare forms to the check so isLoopback returns true regardless of whether the IPv6 address is bracket-wrapped or not.

[nodejs-github-bot]

Review requested:

• @nodejs/net

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.29%. Comparing base (8d0a3b8) to head (ec33f4e).
⚠️ Report is 10 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #63619   +/-   ##
=======================================
  Coverage   90.29%   90.29%           
=======================================
  Files         730      730           
  Lines      234782   234818   +36     
  Branches    43953    43964   +11     
=======================================
+ Hits       211993   212036   +43     
+ Misses      14501    14495    -6     
+ Partials     8288     8287    -1     

Files with missing lines	Coverage Δ
lib/internal/net.js	100.00% <100.00%> (ø)

... and 35 files with indirect coverage changes

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[Ethan-Arrowood]

I believe this change is a valid patch. Can you update the PR description? And maybe add some cases to th eloopbackNot array like ::2 and 0:0:0:0:0:0:0:2 ?