feat(json): optimize UUID encode/decode

[tdakkota]

name          old time/op    new time/op    delta
DecodeUUID-4     173ns ± 3%     148ns ±34%   -14.15%  (p=0.001 n=13+15)
EncodeUUID-4     182ns ± 8%      29ns ±18%   -84.11%  (p=0.000 n=13+15)

name          old speed      new speed      delta
DecodeUUID-4   220MB/s ± 3%   261MB/s ±26%   +18.39%  (p=0.001 n=13+15)
EncodeUUID-4   209MB/s ± 8%  1323MB/s ±16%  +532.72%  (p=0.000 n=13+15)

name          old alloc/op   new alloc/op   delta
DecodeUUID-4     48.0B ± 0%      0.0B       -100.00%  (p=0.000 n=15+15)
EncodeUUID-4     48.0B ± 0%      0.0B       -100.00%  (p=0.000 n=15+15)

name          old allocs/op  new allocs/op  delta
DecodeUUID-4      1.00 ± 0%      0.00       -100.00%  (p=0.000 n=15+15)
EncodeUUID-4      1.00 ± 0%      0.00       -100.00%  (p=0.000 n=15+15)

[codecov]

Codecov Report

Merging #98 (8904bc2) into main (7aacc60) will increase coverage by 0.30%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main      #98      +/-   ##
==========================================
+ Coverage   71.26%   71.56%   +0.30%     
==========================================
  Files          70       70              
  Lines        4005     4048      +43     
==========================================
+ Hits         2854     2897      +43     
  Misses        966      966              
  Partials      185      185              

Impacted Files	Coverage Δ
json/uuid.go	94.11% <100.00%> (+31.61%)	⬆️

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