server: Parse IPs properly for getRemoteAddr

[j0sh]

This supports IPv6 addresses which have multiple colons like [::1]:57579

Discovered while testing with my new laptop which apparently uses IPv6 over localhost.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 31.53858%. Comparing base (9c49266) to head (b36abbb).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@                 Coverage Diff                 @@
##              master       #3790         +/-   ##
===================================================
+ Coverage   31.53331%   31.53858%   +0.00527%     
===================================================
  Files            159         159                 
  Lines          38981       38984          +3     
===================================================
+ Hits           12292       12295          +3     
  Misses         25799       25799                 
  Partials         890         890                 

Files with missing lines	Coverage Δ
server/mediaserver.go	68.14745% <100.00000%> (+0.28015%)	⬆️

... and 2 files with indirect coverage changes

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Files with missing lines	Coverage Δ
server/mediaserver.go	68.14745% <100.00000%> (+0.28015%)	⬆️

... and 2 files with indirect coverage changes

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