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 31.54093%. Comparing base (aca2275) to head (36fd8b8).

Additional details and impacted files

@@                 Coverage Diff                 @@
##              master       #3790         +/-   ##
===================================================
+ Coverage   31.52544%   31.54093%   +0.01549%     
===================================================
  Files            159         159                 
  Lines          47901       47906          +5     
===================================================
+ Hits           15101       15110          +9     
+ Misses         31911       31908          -3     
+ Partials         889         888          -1     

Files with missing lines	Coverage Δ
server/mediaserver.go	67.70045% <100.00000%> (+0.35041%)	⬆️

... and 1 file with indirect coverage changes

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Files with missing lines	Coverage Δ
server/mediaserver.go	67.70045% <100.00000%> (+0.35041%)	⬆️

... and 1 file with indirect coverage changes

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